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