root/fs/hfs/extent.c

DEFINITIONS

1. hfs_ext_build_key
2. hfs_ext_keycmp
3. hfs_ext_find_block
4. hfs_ext_block_count
5. hfs_ext_lastblock
6. __hfs_ext_write_extent
7. hfs_ext_write_extent
8. __hfs_ext_read_extent
9. __hfs_ext_cache_extent
10. hfs_ext_read_extent
11. hfs_dump_extent
12. hfs_add_extent
13. hfs_free_extents
14. hfs_free_fork
15. hfs_get_block
16. hfs_extend_file
17. hfs_file_truncate

   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 int __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 res;
 120                 /* Fail early and avoid ENOSPC during the btree operation */
 121                 res = hfs_bmap_reserve(fd->tree, fd->tree->depth + 1);
 122                 if (res)
 123                         return res;
 124                 hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
 125                 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
 126         } else {
 127                 if (res)
 128                         return res;
 129                 hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength);
 130                 HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY;
 131         }
 132         return 0;
 133 }
 134 
 135 int hfs_ext_write_extent(struct inode *inode)
 136 {
 137         struct hfs_find_data fd;
 138         int res = 0;
 139 
 140         if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
 141                 res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
 142                 if (res)
 143                         return res;
 144                 res = __hfs_ext_write_extent(inode, &fd);
 145                 hfs_find_exit(&fd);
 146         }
 147         return res;
 148 }
 149 
 150 static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
 151                                         u32 cnid, u32 block, u8 type)
 152 {
 153         int res;
 154 
 155         hfs_ext_build_key(fd->search_key, cnid, block, type);
 156         fd->key->ext.FNum = 0;
 157         res = hfs_brec_find(fd);
 158         if (res && res != -ENOENT)
 159                 return res;
 160         if (fd->key->ext.FNum != fd->search_key->ext.FNum ||
 161             fd->key->ext.FkType != fd->search_key->ext.FkType)
 162                 return -ENOENT;
 163         if (fd->entrylength != sizeof(hfs_extent_rec))
 164                 return -EIO;
 165         hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec));
 166         return 0;
 167 }
 168 
 169 static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode *inode, u32 block)
 170 {
 171         int res;
 172 
 173         if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
 174                 res = __hfs_ext_write_extent(inode, fd);
 175                 if (res)
 176                         return res;
 177         }
 178 
 179         res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino,
 180                                     block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
 181         if (!res) {
 182                 HFS_I(inode)->cached_start = be16_to_cpu(fd->key->ext.FABN);
 183                 HFS_I(inode)->cached_blocks = hfs_ext_block_count(HFS_I(inode)->cached_extents);
 184         } else {
 185                 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
 186                 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
 187         }
 188         return res;
 189 }
 190 
 191 static int hfs_ext_read_extent(struct inode *inode, u16 block)
 192 {
 193         struct hfs_find_data fd;
 194         int res;
 195 
 196         if (block >= HFS_I(inode)->cached_start &&
 197             block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
 198                 return 0;
 199 
 200         res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
 201         if (!res) {
 202                 res = __hfs_ext_cache_extent(&fd, inode, block);
 203                 hfs_find_exit(&fd);
 204         }
 205         return res;
 206 }
 207 
 208 static void hfs_dump_extent(struct hfs_extent *extent)
 209 {
 210         int i;
 211 
 212         hfs_dbg(EXTENT, "   ");
 213         for (i = 0; i < 3; i++)
 214                 hfs_dbg_cont(EXTENT, " %u:%u",
 215                              be16_to_cpu(extent[i].block),
 216                              be16_to_cpu(extent[i].count));
 217         hfs_dbg_cont(EXTENT, "\n");
 218 }
 219 
 220 static int hfs_add_extent(struct hfs_extent *extent, u16 offset,
 221                           u16 alloc_block, u16 block_count)
 222 {
 223         u16 count, start;
 224         int i;
 225 
 226         hfs_dump_extent(extent);
 227         for (i = 0; i < 3; extent++, i++) {
 228                 count = be16_to_cpu(extent->count);
 229                 if (offset == count) {
 230                         start = be16_to_cpu(extent->block);
 231                         if (alloc_block != start + count) {
 232                                 if (++i >= 3)
 233                                         return -ENOSPC;
 234                                 extent++;
 235                                 extent->block = cpu_to_be16(alloc_block);
 236                         } else
 237                                 block_count += count;
 238                         extent->count = cpu_to_be16(block_count);
 239                         return 0;
 240                 } else if (offset < count)
 241                         break;
 242                 offset -= count;
 243         }
 244         /* panic? */
 245         return -EIO;
 246 }
 247 
 248 static int hfs_free_extents(struct super_block *sb, struct hfs_extent *extent,
 249                             u16 offset, u16 block_nr)
 250 {
 251         u16 count, start;
 252         int i;
 253 
 254         hfs_dump_extent(extent);
 255         for (i = 0; i < 3; extent++, i++) {
 256                 count = be16_to_cpu(extent->count);
 257                 if (offset == count)
 258                         goto found;
 259                 else if (offset < count)
 260                         break;
 261                 offset -= count;
 262         }
 263         /* panic? */
 264         return -EIO;
 265 found:
 266         for (;;) {
 267                 start = be16_to_cpu(extent->block);
 268                 if (count <= block_nr) {
 269                         hfs_clear_vbm_bits(sb, start, count);
 270                         extent->block = 0;
 271                         extent->count = 0;
 272                         block_nr -= count;
 273                 } else {
 274                         count -= block_nr;
 275                         hfs_clear_vbm_bits(sb, start + count, block_nr);
 276                         extent->count = cpu_to_be16(count);
 277                         block_nr = 0;
 278                 }
 279                 if (!block_nr || !i)
 280                         return 0;
 281                 i--;
 282                 extent--;
 283                 count = be16_to_cpu(extent->count);
 284         }
 285 }
 286 
 287 int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type)
 288 {
 289         struct hfs_find_data fd;
 290         u32 total_blocks, blocks, start;
 291         u32 cnid = be32_to_cpu(file->FlNum);
 292         struct hfs_extent *extent;
 293         int res, i;
 294 
 295         if (type == HFS_FK_DATA) {
 296                 total_blocks = be32_to_cpu(file->PyLen);
 297                 extent = file->ExtRec;
 298         } else {
 299                 total_blocks = be32_to_cpu(file->RPyLen);
 300                 extent = file->RExtRec;
 301         }
 302         total_blocks /= HFS_SB(sb)->alloc_blksz;
 303         if (!total_blocks)
 304                 return 0;
 305 
 306         blocks = 0;
 307         for (i = 0; i < 3; i++)
 308                 blocks += be16_to_cpu(extent[i].count);
 309 
 310         res = hfs_free_extents(sb, extent, blocks, blocks);
 311         if (res)
 312                 return res;
 313         if (total_blocks == blocks)
 314                 return 0;
 315 
 316         res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
 317         if (res)
 318                 return res;
 319         do {
 320                 res = __hfs_ext_read_extent(&fd, extent, cnid, total_blocks, type);
 321                 if (res)
 322                         break;
 323                 start = be16_to_cpu(fd.key->ext.FABN);
 324                 hfs_free_extents(sb, extent, total_blocks - start, total_blocks);
 325                 hfs_brec_remove(&fd);
 326                 total_blocks = start;
 327         } while (total_blocks > blocks);
 328         hfs_find_exit(&fd);
 329 
 330         return res;
 331 }
 332 
 333 /*
 334  * hfs_get_block
 335  */
 336 int hfs_get_block(struct inode *inode, sector_t block,
 337                   struct buffer_head *bh_result, int create)
 338 {
 339         struct super_block *sb;
 340         u16 dblock, ablock;
 341         int res;
 342 
 343         sb = inode->i_sb;
 344         /* Convert inode block to disk allocation block */
 345         ablock = (u32)block / HFS_SB(sb)->fs_div;
 346 
 347         if (block >= HFS_I(inode)->fs_blocks) {
 348                 if (!create)
 349                         return 0;
 350                 if (block > HFS_I(inode)->fs_blocks)
 351                         return -EIO;
 352                 if (ablock >= HFS_I(inode)->alloc_blocks) {
 353                         res = hfs_extend_file(inode);
 354                         if (res)
 355                                 return res;
 356                 }
 357         } else
 358                 create = 0;
 359 
 360         if (ablock < HFS_I(inode)->first_blocks) {
 361                 dblock = hfs_ext_find_block(HFS_I(inode)->first_extents, ablock);
 362                 goto done;
 363         }
 364 
 365         mutex_lock(&HFS_I(inode)->extents_lock);
 366         res = hfs_ext_read_extent(inode, ablock);
 367         if (!res)
 368                 dblock = hfs_ext_find_block(HFS_I(inode)->cached_extents,
 369                                             ablock - HFS_I(inode)->cached_start);
 370         else {
 371                 mutex_unlock(&HFS_I(inode)->extents_lock);
 372                 return -EIO;
 373         }
 374         mutex_unlock(&HFS_I(inode)->extents_lock);
 375 
 376 done:
 377         map_bh(bh_result, sb, HFS_SB(sb)->fs_start +
 378                dblock * HFS_SB(sb)->fs_div +
 379                (u32)block % HFS_SB(sb)->fs_div);
 380 
 381         if (create) {
 382                 set_buffer_new(bh_result);
 383                 HFS_I(inode)->phys_size += sb->s_blocksize;
 384                 HFS_I(inode)->fs_blocks++;
 385                 inode_add_bytes(inode, sb->s_blocksize);
 386                 mark_inode_dirty(inode);
 387         }
 388         return 0;
 389 }
 390 
 391 int hfs_extend_file(struct inode *inode)
 392 {
 393         struct super_block *sb = inode->i_sb;
 394         u32 start, len, goal;
 395         int res;
 396 
 397         mutex_lock(&HFS_I(inode)->extents_lock);
 398         if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks)
 399                 goal = hfs_ext_lastblock(HFS_I(inode)->first_extents);
 400         else {
 401                 res = hfs_ext_read_extent(inode, HFS_I(inode)->alloc_blocks);
 402                 if (res)
 403                         goto out;
 404                 goal = hfs_ext_lastblock(HFS_I(inode)->cached_extents);
 405         }
 406 
 407         len = HFS_I(inode)->clump_blocks;
 408         start = hfs_vbm_search_free(sb, goal, &len);
 409         if (!len) {
 410                 res = -ENOSPC;
 411                 goto out;
 412         }
 413 
 414         hfs_dbg(EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);
 415         if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks) {
 416                 if (!HFS_I(inode)->first_blocks) {
 417                         hfs_dbg(EXTENT, "first extents\n");
 418                         /* no extents yet */
 419                         HFS_I(inode)->first_extents[0].block = cpu_to_be16(start);
 420                         HFS_I(inode)->first_extents[0].count = cpu_to_be16(len);
 421                         res = 0;
 422                 } else {
 423                         /* try to append to extents in inode */
 424                         res = hfs_add_extent(HFS_I(inode)->first_extents,
 425                                              HFS_I(inode)->alloc_blocks,
 426                                              start, len);
 427                         if (res == -ENOSPC)
 428                                 goto insert_extent;
 429                 }
 430                 if (!res) {
 431                         hfs_dump_extent(HFS_I(inode)->first_extents);
 432                         HFS_I(inode)->first_blocks += len;
 433                 }
 434         } else {
 435                 res = hfs_add_extent(HFS_I(inode)->cached_extents,
 436                                      HFS_I(inode)->alloc_blocks -
 437                                      HFS_I(inode)->cached_start,
 438                                      start, len);
 439                 if (!res) {
 440                         hfs_dump_extent(HFS_I(inode)->cached_extents);
 441                         HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
 442                         HFS_I(inode)->cached_blocks += len;
 443                 } else if (res == -ENOSPC)
 444                         goto insert_extent;
 445         }
 446 out:
 447         mutex_unlock(&HFS_I(inode)->extents_lock);
 448         if (!res) {
 449                 HFS_I(inode)->alloc_blocks += len;
 450                 mark_inode_dirty(inode);
 451                 if (inode->i_ino < HFS_FIRSTUSER_CNID)
 452                         set_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags);
 453                 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
 454                 hfs_mark_mdb_dirty(sb);
 455         }
 456         return res;
 457 
 458 insert_extent:
 459         hfs_dbg(EXTENT, "insert new extent\n");
 460         res = hfs_ext_write_extent(inode);
 461         if (res)
 462                 goto out;
 463 
 464         memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
 465         HFS_I(inode)->cached_extents[0].block = cpu_to_be16(start);
 466         HFS_I(inode)->cached_extents[0].count = cpu_to_be16(len);
 467         hfs_dump_extent(HFS_I(inode)->cached_extents);
 468         HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW;
 469         HFS_I(inode)->cached_start = HFS_I(inode)->alloc_blocks;
 470         HFS_I(inode)->cached_blocks = len;
 471 
 472         res = 0;
 473         goto out;
 474 }
 475 
 476 void hfs_file_truncate(struct inode *inode)
 477 {
 478         struct super_block *sb = inode->i_sb;
 479         struct hfs_find_data fd;
 480         u16 blk_cnt, alloc_cnt, start;
 481         u32 size;
 482         int res;
 483 
 484         hfs_dbg(INODE, "truncate: %lu, %Lu -> %Lu\n",
 485                 inode->i_ino, (long long)HFS_I(inode)->phys_size,
 486                 inode->i_size);
 487         if (inode->i_size > HFS_I(inode)->phys_size) {
 488                 struct address_space *mapping = inode->i_mapping;
 489                 void *fsdata;
 490                 struct page *page;
 491 
 492                 /* XXX: Can use generic_cont_expand? */
 493                 size = inode->i_size - 1;
 494                 res = pagecache_write_begin(NULL, mapping, size+1, 0, 0,
 495                                             &page, &fsdata);
 496                 if (!res) {
 497                         res = pagecache_write_end(NULL, mapping, size+1, 0, 0,
 498                                         page, fsdata);
 499                 }
 500                 if (res)
 501                         inode->i_size = HFS_I(inode)->phys_size;
 502                 return;
 503         } else if (inode->i_size == HFS_I(inode)->phys_size)
 504                 return;
 505         size = inode->i_size + HFS_SB(sb)->alloc_blksz - 1;
 506         blk_cnt = size / HFS_SB(sb)->alloc_blksz;
 507         alloc_cnt = HFS_I(inode)->alloc_blocks;
 508         if (blk_cnt == alloc_cnt)
 509                 goto out;
 510 
 511         mutex_lock(&HFS_I(inode)->extents_lock);
 512         res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
 513         if (res) {
 514                 mutex_unlock(&HFS_I(inode)->extents_lock);
 515                 /* XXX: We lack error handling of hfs_file_truncate() */
 516                 return;
 517         }
 518         while (1) {
 519                 if (alloc_cnt == HFS_I(inode)->first_blocks) {
 520                         hfs_free_extents(sb, HFS_I(inode)->first_extents,
 521                                          alloc_cnt, alloc_cnt - blk_cnt);
 522                         hfs_dump_extent(HFS_I(inode)->first_extents);
 523                         HFS_I(inode)->first_blocks = blk_cnt;
 524                         break;
 525                 }
 526                 res = __hfs_ext_cache_extent(&fd, inode, alloc_cnt);
 527                 if (res)
 528                         break;
 529                 start = HFS_I(inode)->cached_start;
 530                 hfs_free_extents(sb, HFS_I(inode)->cached_extents,
 531                                  alloc_cnt - start, alloc_cnt - blk_cnt);
 532                 hfs_dump_extent(HFS_I(inode)->cached_extents);
 533                 if (blk_cnt > start) {
 534                         HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
 535                         break;
 536                 }
 537                 alloc_cnt = start;
 538                 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
 539                 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
 540                 hfs_brec_remove(&fd);
 541         }
 542         hfs_find_exit(&fd);
 543         mutex_unlock(&HFS_I(inode)->extents_lock);
 544 
 545         HFS_I(inode)->alloc_blocks = blk_cnt;
 546 out:
 547         HFS_I(inode)->phys_size = inode->i_size;
 548         HFS_I(inode)->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 549         inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
 550         mark_inode_dirty(inode);
 551 }