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