fs/ext2/ialloc.c

   1 /*
   2  *  linux/fs/ext2/ialloc.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  BSD ufs-inspired inode and directory allocation by
  10  *  Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
  11  *  Big-endian to little-endian byte-swapping/bitmaps by
  12  *        David S. Miller (davem@caip.rutgers.edu), 1995
  13  */
  14
  15 #include <linux/config.h>
  16 #include <linux/fs.h>
  17 #include <linux/ext2_fs.h>
  18 #include <linux/locks.h>
  19 #include <linux/quotaops.h>
  20
  21
  22 /*
  23  * ialloc.c contains the inodes allocation and deallocation routines
  24  */
  25
  26 /*
  27  * The free inodes are managed by bitmaps.  A file system contains several
  28  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  29  * block for inodes, N blocks for the inode table and data blocks.
  30  *
  31  * The file system contains group descriptors which are located after the
  32  * super block.  Each descriptor contains the number of the bitmap block and
  33  * the free blocks count in the block.  The descriptors are loaded in memory
  34  * when a file system is mounted (see ext2_read_super).
  35  */
  36
  37
  38 /*
  39  * Read the inode allocation bitmap for a given block_group, reading
  40  * into the specified slot in the superblock's bitmap cache.
  41  *
  42  * Return >=0 on success or a -ve error code.
  43  */
  44 static int read_inode_bitmap (struct super_block * sb,
  45                                unsigned long block_group,
  46                                unsigned int bitmap_nr)
  47 {
  48         struct ext2_group_desc * gdp;
  49         struct buffer_head * bh = NULL;
  50         int retval = 0;
  51
  52         gdp = ext2_get_group_desc (sb, block_group, NULL);
  53         if (!gdp) {
  54                 retval = -EIO;
  55                 goto error_out;
  56         }
  57         bh = bread (sb->s_dev, le32_to_cpu(gdp->bg_inode_bitmap), sb->s_blocksize);
  58         if (!bh) {
  59                 ext2_error (sb, "read_inode_bitmap",
  60                             "Cannot read inode bitmap - "
  61                             "block_group = %lu, inode_bitmap = %lu",
  62                             block_group, (unsigned long) gdp->bg_inode_bitmap);
  63                 retval = -EIO;
  64         }
  65         /*
  66          * On IO error, just leave a zero in the superblock's block pointer for
  67          * this group.  The IO will be retried next time.
  68          */
  69 error_out:
  70         sb->u.ext2_sb.s_inode_bitmap_number[bitmap_nr] = block_group;
  71         sb->u.ext2_sb.s_inode_bitmap[bitmap_nr] = bh;
  72         return retval;
  73 }
  74
  75 /*
  76  * load_inode_bitmap loads the inode bitmap for a blocks group
  77  *
  78  * It maintains a cache for the last bitmaps loaded.  This cache is managed
  79  * with a LRU algorithm.
  80  *
  81  * Notes:
  82  * 1/ There is one cache per mounted file system.
  83  * 2/ If the file system contains less than EXT2_MAX_GROUP_LOADED groups,
  84  *    this function reads the bitmap without maintaining a LRU cache.
  85  *
  86  * Return the slot used to store the bitmap, or a -ve error code.
  87  */
  88 static int load_inode_bitmap (struct super_block * sb,
  89                               unsigned int block_group)
  90 {
  91         int i, j, retval = 0;
  92         unsigned long inode_bitmap_number;
  93         struct buffer_head * inode_bitmap;
  94
  95         if (block_group >= sb->u.ext2_sb.s_groups_count)
  96                 ext2_panic (sb, "load_inode_bitmap",
  97                             "block_group >= groups_count - "
  98                             "block_group = %d, groups_count = %lu",
  99                              block_group, sb->u.ext2_sb.s_groups_count);
 100         if (sb->u.ext2_sb.s_loaded_inode_bitmaps > 0 &&
 101             sb->u.ext2_sb.s_inode_bitmap_number[0] == block_group &&
 102             sb->u.ext2_sb.s_inode_bitmap[0] != NULL)
 103                 return 0;
 104         if (sb->u.ext2_sb.s_groups_count <= EXT2_MAX_GROUP_LOADED) {
 105                 if (sb->u.ext2_sb.s_inode_bitmap[block_group]) {
 106                         if (sb->u.ext2_sb.s_inode_bitmap_number[block_group] != block_group)
 107                                 ext2_panic (sb, "load_inode_bitmap",
 108                                             "block_group != inode_bitmap_number");
 109                         else
 110                                 return block_group;
 111                 } else {
 112                         retval = read_inode_bitmap (sb, block_group,
 113                                                     block_group);
 114                         if (retval < 0)
 115                                 return retval;
 116                         return block_group;
 117                 }
 118         }
 119
 120         for (i = 0; i < sb->u.ext2_sb.s_loaded_inode_bitmaps &&
 121                     sb->u.ext2_sb.s_inode_bitmap_number[i] != block_group;
 122              i++)
 123                 ;
 124         if (i < sb->u.ext2_sb.s_loaded_inode_bitmaps &&
 125             sb->u.ext2_sb.s_inode_bitmap_number[i] == block_group) {
 126                 inode_bitmap_number = sb->u.ext2_sb.s_inode_bitmap_number[i];
 127                 inode_bitmap = sb->u.ext2_sb.s_inode_bitmap[i];
 128                 for (j = i; j > 0; j--) {
 129                         sb->u.ext2_sb.s_inode_bitmap_number[j] =
 130                                 sb->u.ext2_sb.s_inode_bitmap_number[j - 1];
 131                         sb->u.ext2_sb.s_inode_bitmap[j] =
 132                                 sb->u.ext2_sb.s_inode_bitmap[j - 1];
 133                 }
 134                 sb->u.ext2_sb.s_inode_bitmap_number[0] = inode_bitmap_number;
 135                 sb->u.ext2_sb.s_inode_bitmap[0] = inode_bitmap;
 136
 137                 /*
 138                  * There's still one special case here --- if inode_bitmap == 0
 139                  * then our last attempt to read the bitmap failed and we have
 140                  * just ended up caching that failure.  Try again to read it.
 141                  */
 142                 if (!inode_bitmap)
 143                         retval = read_inode_bitmap (sb, block_group, 0);
 144
 145         } else {
 146                 if (sb->u.ext2_sb.s_loaded_inode_bitmaps < EXT2_MAX_GROUP_LOADED)
 147                         sb->u.ext2_sb.s_loaded_inode_bitmaps++;
 148                 else
 149                         brelse (sb->u.ext2_sb.s_inode_bitmap[EXT2_MAX_GROUP_LOADED - 1]);
 150                 for (j = sb->u.ext2_sb.s_loaded_inode_bitmaps - 1; j > 0; j--) {
 151                         sb->u.ext2_sb.s_inode_bitmap_number[j] =
 152                                 sb->u.ext2_sb.s_inode_bitmap_number[j - 1];
 153                         sb->u.ext2_sb.s_inode_bitmap[j] =
 154                                 sb->u.ext2_sb.s_inode_bitmap[j - 1];
 155                 }
 156                 retval = read_inode_bitmap (sb, block_group, 0);
 157         }
 158         return retval;
 159 }
 160
 161 /*
 162  * NOTE! When we get the inode, we're the only people
 163  * that have access to it, and as such there are no
 164  * race conditions we have to worry about. The inode
 165  * is not on the hash-lists, and it cannot be reached
 166  * through the filesystem because the directory entry
 167  * has been deleted earlier.
 168  *
 169  * HOWEVER: we must make sure that we get no aliases,
 170  * which means that we have to call "clear_inode()"
 171  * _before_ we mark the inode not in use in the inode
 172  * bitmaps. Otherwise a newly created file might use
 173  * the same inode number (not actually the same pointer
 174  * though), and then we'd have two inodes sharing the
 175  * same inode number and space on the harddisk.
 176  */
 177 void ext2_free_inode (struct inode * inode)
 178 {
 179         struct super_block * sb = inode->i_sb;
 180         int is_directory;
 181         unsigned long ino;
 182         struct buffer_head * bh;
 183         struct buffer_head * bh2;
 184         unsigned long block_group;
 185         unsigned long bit;
 186         int bitmap_nr;
 187         struct ext2_group_desc * gdp;
 188         struct ext2_super_block * es;
 189
 190         ino = inode->i_ino;
 191         ext2_debug ("freeing inode %lu\n", ino);
 192
 193         /*
 194          * Note: we must free any quota before locking the superblock,
 195          * as writing the quota to disk may need the lock as well.
 196          */
 197         DQUOT_FREE_INODE(sb, inode);
 198         DQUOT_DROP(inode);
 199
 200         lock_super (sb);
 201         es = sb->u.ext2_sb.s_es;
 202         if (ino < EXT2_FIRST_INO(sb) ||
 203             ino > le32_to_cpu(es->s_inodes_count)) {
 204                 ext2_error (sb, "free_inode",
 205                             "reserved inode or nonexistent inode");
 206                 goto error_return;
 207         }
 208         block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
 209         bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb);
 210         bitmap_nr = load_inode_bitmap (sb, block_group);
 211         if (bitmap_nr < 0)
 212                 goto error_return;
 213
 214         bh = sb->u.ext2_sb.s_inode_bitmap[bitmap_nr];
 215
 216         is_directory = S_ISDIR(inode->i_mode);
 217
 218         /* Do this BEFORE marking the inode not in use */
 219         clear_inode (inode);
 220
 221         /* Ok, now we can actually update the inode bitmaps.. */
 222         if (!ext2_clear_bit (bit, bh->b_data))
 223                 ext2_error (sb, "ext2_free_inode",
 224                               "bit already cleared for inode %lu", ino);
 225         else {
 226                 gdp = ext2_get_group_desc (sb, block_group, &bh2);
 227                 if (gdp) {
 228                         gdp->bg_free_inodes_count =
 229                                 cpu_to_le16(le16_to_cpu(gdp->bg_free_inodes_count) + 1);
 230                         if (is_directory)
 231                                 gdp->bg_used_dirs_count =
 232                                         cpu_to_le16(le16_to_cpu(gdp->bg_used_dirs_count) - 1);
 233                 }
 234                 mark_buffer_dirty(bh2);
 235                 es->s_free_inodes_count =
 236                         cpu_to_le32(le32_to_cpu(es->s_free_inodes_count) + 1);
 237                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
 238         }
 239         mark_buffer_dirty(bh);
 240         if (sb->s_flags & MS_SYNCHRONOUS) {
 241                 ll_rw_block (WRITE, 1, &bh);
 242                 wait_on_buffer (bh);
 243         }
 244         sb->s_dirt = 1;
 245 error_return:
 246         unlock_super (sb);
 247 }
 248
 249 /*
 250  * There are two policies for allocating an inode.  If the new inode is
 251  * a directory, then a forward search is made for a block group with both
 252  * free space and a low directory-to-inode ratio; if that fails, then of
 253  * the groups with above-average free space, that group with the fewest
 254  * directories already is chosen.
 255  *
 256  * For other inodes, search forward from the parent directory\'s block
 257  * group to find a free inode.
 258  */
 259 struct inode * ext2_new_inode (const struct inode * dir, int mode, int * err)
 260 {
 261         struct super_block * sb;
 262         struct buffer_head * bh;
 263         struct buffer_head * bh2;
 264         int i, j, avefreei;
 265         struct inode * inode;
 266         int bitmap_nr;
 267         struct ext2_group_desc * gdp;
 268         struct ext2_group_desc * tmp;
 269         struct ext2_super_block * es;
 270
 271         /* Cannot create files in a deleted directory */
 272         if (!dir || !dir->i_nlink) {
 273                 *err = -EPERM;
 274                 return NULL;
 275         }
 276
 277         sb = dir->i_sb;
 278         inode = new_inode(sb);
 279         if (!inode) {
 280                 *err = -ENOMEM;
 281                 return NULL;
 282         }
 283
 284         lock_super (sb);
 285         es = sb->u.ext2_sb.s_es;
 286 repeat:
 287         gdp = NULL; i=0;
 288
 289         *err = -ENOSPC;
 290         if (S_ISDIR(mode)) {
 291                 avefreei = le32_to_cpu(es->s_free_inodes_count) /
 292                         sb->u.ext2_sb.s_groups_count;
 293 /* I am not yet convinced that this next bit is necessary.
 294                 i = dir->u.ext2_i.i_block_group;
 295                 for (j = 0; j < sb->u.ext2_sb.s_groups_count; j++) {
 296                         tmp = ext2_get_group_desc (sb, i, &bh2);
 297                         if (tmp &&
 298                             (le16_to_cpu(tmp->bg_used_dirs_count) << 8) <
 299                              le16_to_cpu(tmp->bg_free_inodes_count)) {
 300                                 gdp = tmp;
 301                                 break;
 302                         }
 303                         else
 304                         i = ++i % sb->u.ext2_sb.s_groups_count;
 305                 }
 306 */
 307                 if (!gdp) {
 308                         for (j = 0; j < sb->u.ext2_sb.s_groups_count; j++) {
 309                                 tmp = ext2_get_group_desc (sb, j, &bh2);
 310                                 if (tmp &&
 311                                     le16_to_cpu(tmp->bg_free_inodes_count) &&
 312                                     le16_to_cpu(tmp->bg_free_inodes_count) >= avefreei) {
 313                                         if (!gdp ||
 314                                             (le16_to_cpu(tmp->bg_free_blocks_count) >
 315                                              le16_to_cpu(gdp->bg_free_blocks_count))) {
 316                                                 i = j;
 317                                                 gdp = tmp;
 318                                         }
 319                                 }
 320                         }
 321                 }
 322         }
 323         else
 324         {
 325                 /*
 326                  * Try to place the inode in its parent directory
 327                  */
 328                 i = dir->u.ext2_i.i_block_group;
 329                 tmp = ext2_get_group_desc (sb, i, &bh2);
 330                 if (tmp && le16_to_cpu(tmp->bg_free_inodes_count))
 331                         gdp = tmp;
 332                 else
 333                 {
 334                         /*
 335                          * Use a quadratic hash to find a group with a
 336                          * free inode
 337                          */
 338                         for (j = 1; j < sb->u.ext2_sb.s_groups_count; j <<= 1) {
 339                                 i += j;
 340                                 if (i >= sb->u.ext2_sb.s_groups_count)
 341                                         i -= sb->u.ext2_sb.s_groups_count;
 342                                 tmp = ext2_get_group_desc (sb, i, &bh2);
 343                                 if (tmp &&
 344                                     le16_to_cpu(tmp->bg_free_inodes_count)) {
 345                                         gdp = tmp;
 346                                         break;
 347                                 }
 348                         }
 349                 }
 350                 if (!gdp) {
 351                         /*
 352                          * That failed: try linear search for a free inode
 353                          */
 354                         i = dir->u.ext2_i.i_block_group + 1;
 355                         for (j = 2; j < sb->u.ext2_sb.s_groups_count; j++) {
 356                                 if (++i >= sb->u.ext2_sb.s_groups_count)
 357                                         i = 0;
 358                                 tmp = ext2_get_group_desc (sb, i, &bh2);
 359                                 if (tmp &&
 360                                     le16_to_cpu(tmp->bg_free_inodes_count)) {
 361                                         gdp = tmp;
 362                                         break;
 363                                 }
 364                         }
 365                 }
 366         }
 367
 368         if (!gdp) {
 369                 unlock_super (sb);
 370                 iput(inode);
 371                 return NULL;
 372         }
 373         bitmap_nr = load_inode_bitmap (sb, i);
 374         if (bitmap_nr < 0) {
 375                 unlock_super (sb);
 376                 iput(inode);
 377                 *err = -EIO;
 378                 return NULL;
 379         }
 380
 381         bh = sb->u.ext2_sb.s_inode_bitmap[bitmap_nr];
 382         if ((j = ext2_find_first_zero_bit ((unsigned long *) bh->b_data,
 383                                       EXT2_INODES_PER_GROUP(sb))) <
 384             EXT2_INODES_PER_GROUP(sb)) {
 385                 if (ext2_set_bit (j, bh->b_data)) {
 386                         ext2_error (sb, "ext2_new_inode",
 387                                       "bit already set for inode %d", j);
 388                         goto repeat;
 389                 }
 390                 mark_buffer_dirty(bh);
 391                 if (sb->s_flags & MS_SYNCHRONOUS) {
 392                         ll_rw_block (WRITE, 1, &bh);
 393                         wait_on_buffer (bh);
 394                 }
 395         } else {
 396                 if (le16_to_cpu(gdp->bg_free_inodes_count) != 0) {
 397                         ext2_error (sb, "ext2_new_inode",
 398                                     "Free inodes count corrupted in group %d",
 399                                     i);
 400                         if (sb->s_flags & MS_RDONLY) {
 401                                 unlock_super (sb);
 402                                 iput (inode);
 403                                 return NULL;
 404                         }
 405                         gdp->bg_free_inodes_count = 0;
 406                         mark_buffer_dirty(bh2);
 407                 }
 408                 goto repeat;
 409         }
 410         j += i * EXT2_INODES_PER_GROUP(sb) + 1;
 411         if (j < EXT2_FIRST_INO(sb) || j > le32_to_cpu(es->s_inodes_count)) {
 412                 ext2_error (sb, "ext2_new_inode",
 413                             "reserved inode or inode > inodes count - "
 414                             "block_group = %d,inode=%d", i, j);
 415                 unlock_super (sb);
 416                 iput (inode);
 417                 *err = -EIO;
 418                 return NULL;
 419         }
 420         gdp->bg_free_inodes_count =
 421                 cpu_to_le16(le16_to_cpu(gdp->bg_free_inodes_count) - 1);
 422         if (S_ISDIR(mode))
 423                 gdp->bg_used_dirs_count =
 424                         cpu_to_le16(le16_to_cpu(gdp->bg_used_dirs_count) + 1);
 425         mark_buffer_dirty(bh2);
 426         es->s_free_inodes_count =
 427                 cpu_to_le32(le32_to_cpu(es->s_free_inodes_count) - 1);
 428         mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
 429         sb->s_dirt = 1;
 430         inode->i_mode = mode;
 431         inode->i_uid = current->fsuid;
 432         if (test_opt (sb, GRPID))
 433                 inode->i_gid = dir->i_gid;
 434         else if (dir->i_mode & S_ISGID) {
 435                 inode->i_gid = dir->i_gid;
 436                 if (S_ISDIR(mode))
 437                         mode |= S_ISGID;
 438         } else
 439                 inode->i_gid = current->fsgid;
 440
 441         inode->i_ino = j;
 442         inode->i_blksize = PAGE_SIZE;   /* This is the optimal IO size (for stat), not the fs block size */
 443         inode->i_blocks = 0;
 444         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 445         inode->u.ext2_i.i_new_inode = 1;
 446         inode->u.ext2_i.i_flags = dir->u.ext2_i.i_flags;
 447         if (S_ISLNK(mode))
 448                 inode->u.ext2_i.i_flags &= ~(EXT2_IMMUTABLE_FL | EXT2_APPEND_FL);
 449         inode->u.ext2_i.i_faddr = 0;
 450         inode->u.ext2_i.i_frag_no = 0;
 451         inode->u.ext2_i.i_frag_size = 0;
 452         inode->u.ext2_i.i_file_acl = 0;
 453         inode->u.ext2_i.i_dir_acl = 0;
 454         inode->u.ext2_i.i_dtime = 0;
 455         inode->u.ext2_i.i_block_group = i;
 456         if (inode->u.ext2_i.i_flags & EXT2_SYNC_FL)
 457                 inode->i_flags |= S_SYNC;
 458         insert_inode_hash(inode);
 459         inode->i_generation = event++;
 460         mark_inode_dirty(inode);
 461
 462         unlock_super (sb);
 463         if(DQUOT_ALLOC_INODE(sb, inode)) {
 464                 sb->dq_op->drop(inode);
 465                 inode->i_nlink = 0;
 466                 iput(inode);
 467                 *err = -EDQUOT;
 468                 return NULL;
 469         }
 470         ext2_debug ("allocating inode %lu\n", inode->i_ino);
 471
 472         *err = 0;
 473         return inode;
 474 }
 475
 476 unsigned long ext2_count_free_inodes (struct super_block * sb)
 477 {
 478 #ifdef EXT2FS_DEBUG
 479         struct ext2_super_block * es;
 480         unsigned long desc_count, bitmap_count, x;
 481         int bitmap_nr;
 482         struct ext2_group_desc * gdp;
 483         int i;
 484
 485         lock_super (sb);
 486         es = sb->u.ext2_sb.s_es;
 487         desc_count = 0;
 488         bitmap_count = 0;
 489         gdp = NULL;
 490         for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++) {
 491                 gdp = ext2_get_group_desc (sb, i, NULL);
 492                 if (!gdp)
 493                         continue;
 494                 desc_count += le16_to_cpu(gdp->bg_free_inodes_count);
 495                 bitmap_nr = load_inode_bitmap (sb, i);
 496                 if (bitmap_nr < 0)
 497                         continue;
 498
 499                 x = ext2_count_free (sb->u.ext2_sb.s_inode_bitmap[bitmap_nr],
 500                                      EXT2_INODES_PER_GROUP(sb) / 8);
 501                 printk ("group %d: stored = %d, counted = %lu\n",
 502                         i, le16_to_cpu(gdp->bg_free_inodes_count), x);
 503                 bitmap_count += x;
 504         }
 505         printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
 506                 le32_to_cpu(es->s_free_inodes_count), desc_count, bitmap_count);
 507         unlock_super (sb);
 508         return desc_count;
 509 #else
 510         return le32_to_cpu(sb->u.ext2_sb.s_es->s_free_inodes_count);
 511 #endif
 512 }
 513
 514 #ifdef CONFIG_EXT2_CHECK
 515 /* Called at mount-time, super-block is locked */
 516 void ext2_check_inodes_bitmap (struct super_block * sb)
 517 {
 518         struct ext2_super_block * es;
 519         unsigned long desc_count, bitmap_count, x;
 520         int bitmap_nr;
 521         struct ext2_group_desc * gdp;
 522         int i;
 523
 524         es = sb->u.ext2_sb.s_es;
 525         desc_count = 0;
 526         bitmap_count = 0;
 527         gdp = NULL;
 528         for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++) {
 529                 gdp = ext2_get_group_desc (sb, i, NULL);
 530                 if (!gdp)
 531                         continue;
 532                 desc_count += le16_to_cpu(gdp->bg_free_inodes_count);
 533                 bitmap_nr = load_inode_bitmap (sb, i);
 534                 if (bitmap_nr < 0)
 535                         continue;
 536
 537                 x = ext2_count_free (sb->u.ext2_sb.s_inode_bitmap[bitmap_nr],
 538                                      EXT2_INODES_PER_GROUP(sb) / 8);
 539                 if (le16_to_cpu(gdp->bg_free_inodes_count) != x)
 540                         ext2_error (sb, "ext2_check_inodes_bitmap",
 541                                     "Wrong free inodes count in group %d, "
 542                                     "stored = %d, counted = %lu", i,
 543                                     le16_to_cpu(gdp->bg_free_inodes_count), x);
 544                 bitmap_count += x;
 545         }
 546         if (le32_to_cpu(es->s_free_inodes_count) != bitmap_count)
 547                 ext2_error (sb, "ext2_check_inodes_bitmap",
 548                             "Wrong free inodes count in super block, "
 549                             "stored = %lu, counted = %lu",
 550                             (unsigned long) le32_to_cpu(es->s_free_inodes_count),
 551                             bitmap_count);
 552 }
 553 #endif