git.oblomov.eu Git - linux-2.6/blob - fs/hfs/extent.c

   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 }