fs/ext3/resize.c

   1 /*
   2  *  linux/fs/ext3/resize.c
   3  *
   4  * Support for resizing an ext3 filesystem while it is mounted.
   5  *
   6  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
   7  *
   8  * This could probably be made into a module, because it is not often in use.
   9  */
  10
  11
  12 #define EXT3FS_DEBUG
  13
  14 #include <linux/ext3_jbd.h>
  15
  16 #include <linux/errno.h>
  17 #include <linux/slab.h>
  18
  19
  20 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  21 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  22
  23 static int verify_group_input(struct super_block *sb,
  24                               struct ext3_new_group_data *input)
  25 {
  26         struct ext3_sb_info *sbi = EXT3_SB(sb);
  27         struct ext3_super_block *es = sbi->s_es;
  28         ext3_fsblk_t start = le32_to_cpu(es->s_blocks_count);
  29         ext3_fsblk_t end = start + input->blocks_count;
  30         unsigned group = input->group;
  31         ext3_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  32         unsigned overhead = ext3_bg_has_super(sb, group) ?
  33                 (1 + ext3_bg_num_gdb(sb, group) +
  34                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  35         ext3_fsblk_t metaend = start + overhead;
  36         struct buffer_head *bh = NULL;
  37         ext3_grpblk_t free_blocks_count;
  38         int err = -EINVAL;
  39
  40         input->free_blocks_count = free_blocks_count =
  41                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  42
  43         if (test_opt(sb, DEBUG))
  44                 printk(KERN_DEBUG "EXT3-fs: adding %s group %u: %u blocks "
  45                        "(%d free, %u reserved)\n",
  46                        ext3_bg_has_super(sb, input->group) ? "normal" :
  47                        "no-super", input->group, input->blocks_count,
  48                        free_blocks_count, input->reserved_blocks);
  49
  50         if (group != sbi->s_groups_count)
  51                 ext3_warning(sb, __FUNCTION__,
  52                              "Cannot add at group %u (only %lu groups)",
  53                              input->group, sbi->s_groups_count);
  54         else if ((start - le32_to_cpu(es->s_first_data_block)) %
  55                  EXT3_BLOCKS_PER_GROUP(sb))
  56                 ext3_warning(sb, __FUNCTION__, "Last group not full");
  57         else if (input->reserved_blocks > input->blocks_count / 5)
  58                 ext3_warning(sb, __FUNCTION__, "Reserved blocks too high (%u)",
  59                              input->reserved_blocks);
  60         else if (free_blocks_count < 0)
  61                 ext3_warning(sb, __FUNCTION__, "Bad blocks count %u",
  62                              input->blocks_count);
  63         else if (!(bh = sb_bread(sb, end - 1)))
  64                 ext3_warning(sb, __FUNCTION__,
  65                              "Cannot read last block ("E3FSBLK")",
  66                              end - 1);
  67         else if (outside(input->block_bitmap, start, end))
  68                 ext3_warning(sb, __FUNCTION__,
  69                              "Block bitmap not in group (block %u)",
  70                              input->block_bitmap);
  71         else if (outside(input->inode_bitmap, start, end))
  72                 ext3_warning(sb, __FUNCTION__,
  73                              "Inode bitmap not in group (block %u)",
  74                              input->inode_bitmap);
  75         else if (outside(input->inode_table, start, end) ||
  76                  outside(itend - 1, start, end))
  77                 ext3_warning(sb, __FUNCTION__,
  78                              "Inode table not in group (blocks %u-"E3FSBLK")",
  79                              input->inode_table, itend - 1);
  80         else if (input->inode_bitmap == input->block_bitmap)
  81                 ext3_warning(sb, __FUNCTION__,
  82                              "Block bitmap same as inode bitmap (%u)",
  83                              input->block_bitmap);
  84         else if (inside(input->block_bitmap, input->inode_table, itend))
  85                 ext3_warning(sb, __FUNCTION__,
  86                              "Block bitmap (%u) in inode table (%u-"E3FSBLK")",
  87                              input->block_bitmap, input->inode_table, itend-1);
  88         else if (inside(input->inode_bitmap, input->inode_table, itend))
  89                 ext3_warning(sb, __FUNCTION__,
  90                              "Inode bitmap (%u) in inode table (%u-"E3FSBLK")",
  91                              input->inode_bitmap, input->inode_table, itend-1);
  92         else if (inside(input->block_bitmap, start, metaend))
  93                 ext3_warning(sb, __FUNCTION__,
  94                              "Block bitmap (%u) in GDT table"
  95                              " ("E3FSBLK"-"E3FSBLK")",
  96                              input->block_bitmap, start, metaend - 1);
  97         else if (inside(input->inode_bitmap, start, metaend))
  98                 ext3_warning(sb, __FUNCTION__,
  99                              "Inode bitmap (%u) in GDT table"
 100                              " ("E3FSBLK"-"E3FSBLK")",
 101                              input->inode_bitmap, start, metaend - 1);
 102         else if (inside(input->inode_table, start, metaend) ||
 103                  inside(itend - 1, start, metaend))
 104                 ext3_warning(sb, __FUNCTION__,
 105                              "Inode table (%u-"E3FSBLK") overlaps"
 106                              "GDT table ("E3FSBLK"-"E3FSBLK")",
 107                              input->inode_table, itend - 1, start, metaend - 1);
 108         else
 109                 err = 0;
 110         brelse(bh);
 111
 112         return err;
 113 }
 114
 115 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 116                                   ext3_fsblk_t blk)
 117 {
 118         struct buffer_head *bh;
 119         int err;
 120
 121         bh = sb_getblk(sb, blk);
 122         if (!bh)
 123                 return ERR_PTR(-EIO);
 124         if ((err = ext3_journal_get_write_access(handle, bh))) {
 125                 brelse(bh);
 126                 bh = ERR_PTR(err);
 127         } else {
 128                 lock_buffer(bh);
 129                 memset(bh->b_data, 0, sb->s_blocksize);
 130                 set_buffer_uptodate(bh);
 131                 unlock_buffer(bh);
 132         }
 133
 134         return bh;
 135 }
 136
 137 /*
 138  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 139  * need to use it within a single byte (to ensure we get endianness right).
 140  * We can use memset for the rest of the bitmap as there are no other users.
 141  */
 142 static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 143 {
 144         int i;
 145
 146         if (start_bit >= end_bit)
 147                 return;
 148
 149         ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 150         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 151                 ext3_set_bit(i, bitmap);
 152         if (i < end_bit)
 153                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 154 }
 155
 156 /*
 157  * If we have fewer than thresh credits, extend by EXT3_MAX_TRANS_DATA.
 158  * If that fails, restart the transaction & regain write access for the
 159  * buffer head which is used for block_bitmap modifications.
 160  */
 161 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 162                                          struct buffer_head *bh)
 163 {
 164         int err;
 165
 166         if (handle->h_buffer_credits >= thresh)
 167                 return 0;
 168
 169         err = ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA);
 170         if (err < 0)
 171                 return err;
 172         if (err) {
 173                 err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA);
 174                 if (err)
 175                         return err;
 176                 err = ext3_journal_get_write_access(handle, bh);
 177                 if (err)
 178                         return err;
 179         }
 180
 181         return 0;
 182 }
 183
 184 /*
 185  * Set up the block and inode bitmaps, and the inode table for the new group.
 186  * This doesn't need to be part of the main transaction, since we are only
 187  * changing blocks outside the actual filesystem.  We still do journaling to
 188  * ensure the recovery is correct in case of a failure just after resize.
 189  * If any part of this fails, we simply abort the resize.
 190  */
 191 static int setup_new_group_blocks(struct super_block *sb,
 192                                   struct ext3_new_group_data *input)
 193 {
 194         struct ext3_sb_info *sbi = EXT3_SB(sb);
 195         ext3_fsblk_t start = ext3_group_first_block_no(sb, input->group);
 196         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 197                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 198         unsigned long gdblocks = ext3_bg_num_gdb(sb, input->group);
 199         struct buffer_head *bh;
 200         handle_t *handle;
 201         ext3_fsblk_t block;
 202         ext3_grpblk_t bit;
 203         int i;
 204         int err = 0, err2;
 205
 206         /* This transaction may be extended/restarted along the way */
 207         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 208
 209         if (IS_ERR(handle))
 210                 return PTR_ERR(handle);
 211
 212         lock_super(sb);
 213         if (input->group != sbi->s_groups_count) {
 214                 err = -EBUSY;
 215                 goto exit_journal;
 216         }
 217
 218         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 219                 err = PTR_ERR(bh);
 220                 goto exit_journal;
 221         }
 222
 223         if (ext3_bg_has_super(sb, input->group)) {
 224                 ext3_debug("mark backup superblock %#04lx (+0)\n", start);
 225                 ext3_set_bit(0, bh->b_data);
 226         }
 227
 228         /* Copy all of the GDT blocks into the backup in this group */
 229         for (i = 0, bit = 1, block = start + 1;
 230              i < gdblocks; i++, block++, bit++) {
 231                 struct buffer_head *gdb;
 232
 233                 ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
 234
 235                 err = extend_or_restart_transaction(handle, 1, bh);
 236                 if (err)
 237                         goto exit_bh;
 238
 239                 gdb = sb_getblk(sb, block);
 240                 if (!gdb) {
 241                         err = -EIO;
 242                         goto exit_bh;
 243                 }
 244                 if ((err = ext3_journal_get_write_access(handle, gdb))) {
 245                         brelse(gdb);
 246                         goto exit_bh;
 247                 }
 248                 lock_buffer(bh);
 249                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, bh->b_size);
 250                 set_buffer_uptodate(gdb);
 251                 unlock_buffer(bh);
 252                 ext3_journal_dirty_metadata(handle, gdb);
 253                 ext3_set_bit(bit, bh->b_data);
 254                 brelse(gdb);
 255         }
 256
 257         /* Zero out all of the reserved backup group descriptor table blocks */
 258         for (i = 0, bit = gdblocks + 1, block = start + bit;
 259              i < reserved_gdb; i++, block++, bit++) {
 260                 struct buffer_head *gdb;
 261
 262                 ext3_debug("clear reserved block %#04lx (+%d)\n", block, bit);
 263
 264                 err = extend_or_restart_transaction(handle, 1, bh);
 265                 if (err)
 266                         goto exit_bh;
 267
 268                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 269                         err = PTR_ERR(bh);
 270                         goto exit_bh;
 271                 }
 272                 ext3_journal_dirty_metadata(handle, gdb);
 273                 ext3_set_bit(bit, bh->b_data);
 274                 brelse(gdb);
 275         }
 276         ext3_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
 277                    input->block_bitmap - start);
 278         ext3_set_bit(input->block_bitmap - start, bh->b_data);
 279         ext3_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
 280                    input->inode_bitmap - start);
 281         ext3_set_bit(input->inode_bitmap - start, bh->b_data);
 282
 283         /* Zero out all of the inode table blocks */
 284         for (i = 0, block = input->inode_table, bit = block - start;
 285              i < sbi->s_itb_per_group; i++, bit++, block++) {
 286                 struct buffer_head *it;
 287
 288                 ext3_debug("clear inode block %#04lx (+%d)\n", block, bit);
 289
 290                 err = extend_or_restart_transaction(handle, 1, bh);
 291                 if (err)
 292                         goto exit_bh;
 293
 294                 if (IS_ERR(it = bclean(handle, sb, block))) {
 295                         err = PTR_ERR(it);
 296                         goto exit_bh;
 297                 }
 298                 ext3_journal_dirty_metadata(handle, it);
 299                 brelse(it);
 300                 ext3_set_bit(bit, bh->b_data);
 301         }
 302
 303         err = extend_or_restart_transaction(handle, 2, bh);
 304         if (err)
 305                 goto exit_bh;
 306
 307         mark_bitmap_end(input->blocks_count, EXT3_BLOCKS_PER_GROUP(sb),
 308                         bh->b_data);
 309         ext3_journal_dirty_metadata(handle, bh);
 310         brelse(bh);
 311
 312         /* Mark unused entries in inode bitmap used */
 313         ext3_debug("clear inode bitmap %#04x (+%ld)\n",
 314                    input->inode_bitmap, input->inode_bitmap - start);
 315         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 316                 err = PTR_ERR(bh);
 317                 goto exit_journal;
 318         }
 319
 320         mark_bitmap_end(EXT3_INODES_PER_GROUP(sb), EXT3_BLOCKS_PER_GROUP(sb),
 321                         bh->b_data);
 322         ext3_journal_dirty_metadata(handle, bh);
 323 exit_bh:
 324         brelse(bh);
 325
 326 exit_journal:
 327         unlock_super(sb);
 328         if ((err2 = ext3_journal_stop(handle)) && !err)
 329                 err = err2;
 330
 331         return err;
 332 }
 333
 334 /*
 335  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 336  * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
 337  * calling this for the first time.  In a sparse filesystem it will be the
 338  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 339  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 340  */
 341 static unsigned ext3_list_backups(struct super_block *sb, unsigned *three,
 342                                   unsigned *five, unsigned *seven)
 343 {
 344         unsigned *min = three;
 345         int mult = 3;
 346         unsigned ret;
 347
 348         if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
 349                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 350                 ret = *min;
 351                 *min += 1;
 352                 return ret;
 353         }
 354
 355         if (*five < *min) {
 356                 min = five;
 357                 mult = 5;
 358         }
 359         if (*seven < *min) {
 360                 min = seven;
 361                 mult = 7;
 362         }
 363
 364         ret = *min;
 365         *min *= mult;
 366
 367         return ret;
 368 }
 369
 370 /*
 371  * Check that all of the backup GDT blocks are held in the primary GDT block.
 372  * It is assumed that they are stored in group order.  Returns the number of
 373  * groups in current filesystem that have BACKUPS, or -ve error code.
 374  */
 375 static int verify_reserved_gdb(struct super_block *sb,
 376                                struct buffer_head *primary)
 377 {
 378         const ext3_fsblk_t blk = primary->b_blocknr;
 379         const unsigned long end = EXT3_SB(sb)->s_groups_count;
 380         unsigned three = 1;
 381         unsigned five = 5;
 382         unsigned seven = 7;
 383         unsigned grp;
 384         __le32 *p = (__le32 *)primary->b_data;
 385         int gdbackups = 0;
 386
 387         while ((grp = ext3_list_backups(sb, &three, &five, &seven)) < end) {
 388                 if (le32_to_cpu(*p++) != grp * EXT3_BLOCKS_PER_GROUP(sb) + blk){
 389                         ext3_warning(sb, __FUNCTION__,
 390                                      "reserved GDT "E3FSBLK
 391                                      " missing grp %d ("E3FSBLK")",
 392                                      blk, grp,
 393                                      grp * EXT3_BLOCKS_PER_GROUP(sb) + blk);
 394                         return -EINVAL;
 395                 }
 396                 if (++gdbackups > EXT3_ADDR_PER_BLOCK(sb))
 397                         return -EFBIG;
 398         }
 399
 400         return gdbackups;
 401 }
 402
 403 /*
 404  * Called when we need to bring a reserved group descriptor table block into
 405  * use from the resize inode.  The primary copy of the new GDT block currently
 406  * is an indirect block (under the double indirect block in the resize inode).
 407  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 408  * block, in group order.  Even though we know all the block numbers we need,
 409  * we check to ensure that the resize inode has actually reserved these blocks.
 410  *
 411  * Don't need to update the block bitmaps because the blocks are still in use.
 412  *
 413  * We get all of the error cases out of the way, so that we are sure to not
 414  * fail once we start modifying the data on disk, because JBD has no rollback.
 415  */
 416 static int add_new_gdb(handle_t *handle, struct inode *inode,
 417                        struct ext3_new_group_data *input,
 418                        struct buffer_head **primary)
 419 {
 420         struct super_block *sb = inode->i_sb;
 421         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
 422         unsigned long gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 423         ext3_fsblk_t gdblock = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 424         struct buffer_head **o_group_desc, **n_group_desc;
 425         struct buffer_head *dind;
 426         int gdbackups;
 427         struct ext3_iloc iloc;
 428         __le32 *data;
 429         int err;
 430
 431         if (test_opt(sb, DEBUG))
 432                 printk(KERN_DEBUG
 433                        "EXT3-fs: ext3_add_new_gdb: adding group block %lu\n",
 434                        gdb_num);
 435
 436         /*
 437          * If we are not using the primary superblock/GDT copy don't resize,
 438          * because the user tools have no way of handling this.  Probably a
 439          * bad time to do it anyways.
 440          */
 441         if (EXT3_SB(sb)->s_sbh->b_blocknr !=
 442             le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) {
 443                 ext3_warning(sb, __FUNCTION__,
 444                         "won't resize using backup superblock at %llu",
 445                         (unsigned long long)EXT3_SB(sb)->s_sbh->b_blocknr);
 446                 return -EPERM;
 447         }
 448
 449         *primary = sb_bread(sb, gdblock);
 450         if (!*primary)
 451                 return -EIO;
 452
 453         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 454                 err = gdbackups;
 455                 goto exit_bh;
 456         }
 457
 458         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 459         dind = sb_bread(sb, le32_to_cpu(*data));
 460         if (!dind) {
 461                 err = -EIO;
 462                 goto exit_bh;
 463         }
 464
 465         data = (__le32 *)dind->b_data;
 466         if (le32_to_cpu(data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)]) != gdblock) {
 467                 ext3_warning(sb, __FUNCTION__,
 468                              "new group %u GDT block "E3FSBLK" not reserved",
 469                              input->group, gdblock);
 470                 err = -EINVAL;
 471                 goto exit_dind;
 472         }
 473
 474         if ((err = ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh)))
 475                 goto exit_dind;
 476
 477         if ((err = ext3_journal_get_write_access(handle, *primary)))
 478                 goto exit_sbh;
 479
 480         if ((err = ext3_journal_get_write_access(handle, dind)))
 481                 goto exit_primary;
 482
 483         /* ext3_reserve_inode_write() gets a reference on the iloc */
 484         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 485                 goto exit_dindj;
 486
 487         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 488                         GFP_KERNEL);
 489         if (!n_group_desc) {
 490                 err = -ENOMEM;
 491                 ext3_warning (sb, __FUNCTION__,
 492                               "not enough memory for %lu groups", gdb_num + 1);
 493                 goto exit_inode;
 494         }
 495
 496         /*
 497          * Finally, we have all of the possible failures behind us...
 498          *
 499          * Remove new GDT block from inode double-indirect block and clear out
 500          * the new GDT block for use (which also "frees" the backup GDT blocks
 501          * from the reserved inode).  We don't need to change the bitmaps for
 502          * these blocks, because they are marked as in-use from being in the
 503          * reserved inode, and will become GDT blocks (primary and backup).
 504          */
 505         data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)] = 0;
 506         ext3_journal_dirty_metadata(handle, dind);
 507         brelse(dind);
 508         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 509         ext3_mark_iloc_dirty(handle, inode, &iloc);
 510         memset((*primary)->b_data, 0, sb->s_blocksize);
 511         ext3_journal_dirty_metadata(handle, *primary);
 512
 513         o_group_desc = EXT3_SB(sb)->s_group_desc;
 514         memcpy(n_group_desc, o_group_desc,
 515                EXT3_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 516         n_group_desc[gdb_num] = *primary;
 517         EXT3_SB(sb)->s_group_desc = n_group_desc;
 518         EXT3_SB(sb)->s_gdb_count++;
 519         kfree(o_group_desc);
 520
 521         es->s_reserved_gdt_blocks =
 522                 cpu_to_le16(le16_to_cpu(es->s_reserved_gdt_blocks) - 1);
 523         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 524
 525         return 0;
 526
 527 exit_inode:
 528         //ext3_journal_release_buffer(handle, iloc.bh);
 529         brelse(iloc.bh);
 530 exit_dindj:
 531         //ext3_journal_release_buffer(handle, dind);
 532 exit_primary:
 533         //ext3_journal_release_buffer(handle, *primary);
 534 exit_sbh:
 535         //ext3_journal_release_buffer(handle, *primary);
 536 exit_dind:
 537         brelse(dind);
 538 exit_bh:
 539         brelse(*primary);
 540
 541         ext3_debug("leaving with error %d\n", err);
 542         return err;
 543 }
 544
 545 /*
 546  * Called when we are adding a new group which has a backup copy of each of
 547  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 548  * We need to add these reserved backup GDT blocks to the resize inode, so
 549  * that they are kept for future resizing and not allocated to files.
 550  *
 551  * Each reserved backup GDT block will go into a different indirect block.
 552  * The indirect blocks are actually the primary reserved GDT blocks,
 553  * so we know in advance what their block numbers are.  We only get the
 554  * double-indirect block to verify it is pointing to the primary reserved
 555  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 556  * backup GDT blocks are stored in their reserved primary GDT block.
 557  */
 558 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 559                               struct ext3_new_group_data *input)
 560 {
 561         struct super_block *sb = inode->i_sb;
 562         int reserved_gdb =le16_to_cpu(EXT3_SB(sb)->s_es->s_reserved_gdt_blocks);
 563         struct buffer_head **primary;
 564         struct buffer_head *dind;
 565         struct ext3_iloc iloc;
 566         ext3_fsblk_t blk;
 567         __le32 *data, *end;
 568         int gdbackups = 0;
 569         int res, i;
 570         int err;
 571
 572         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_KERNEL);
 573         if (!primary)
 574                 return -ENOMEM;
 575
 576         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 577         dind = sb_bread(sb, le32_to_cpu(*data));
 578         if (!dind) {
 579                 err = -EIO;
 580                 goto exit_free;
 581         }
 582
 583         blk = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + EXT3_SB(sb)->s_gdb_count;
 584         data = (__le32 *)dind->b_data + EXT3_SB(sb)->s_gdb_count;
 585         end = (__le32 *)dind->b_data + EXT3_ADDR_PER_BLOCK(sb);
 586
 587         /* Get each reserved primary GDT block and verify it holds backups */
 588         for (res = 0; res < reserved_gdb; res++, blk++) {
 589                 if (le32_to_cpu(*data) != blk) {
 590                         ext3_warning(sb, __FUNCTION__,
 591                                      "reserved block "E3FSBLK
 592                                      " not at offset %ld",
 593                                      blk,
 594                                      (long)(data - (__le32 *)dind->b_data));
 595                         err = -EINVAL;
 596                         goto exit_bh;
 597                 }
 598                 primary[res] = sb_bread(sb, blk);
 599                 if (!primary[res]) {
 600                         err = -EIO;
 601                         goto exit_bh;
 602                 }
 603                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 604                         brelse(primary[res]);
 605                         err = gdbackups;
 606                         goto exit_bh;
 607                 }
 608                 if (++data >= end)
 609                         data = (__le32 *)dind->b_data;
 610         }
 611
 612         for (i = 0; i < reserved_gdb; i++) {
 613                 if ((err = ext3_journal_get_write_access(handle, primary[i]))) {
 614                         /*
 615                         int j;
 616                         for (j = 0; j < i; j++)
 617                                 ext3_journal_release_buffer(handle, primary[j]);
 618                          */
 619                         goto exit_bh;
 620                 }
 621         }
 622
 623         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 624                 goto exit_bh;
 625
 626         /*
 627          * Finally we can add each of the reserved backup GDT blocks from
 628          * the new group to its reserved primary GDT block.
 629          */
 630         blk = input->group * EXT3_BLOCKS_PER_GROUP(sb);
 631         for (i = 0; i < reserved_gdb; i++) {
 632                 int err2;
 633                 data = (__le32 *)primary[i]->b_data;
 634                 /* printk("reserving backup %lu[%u] = %lu\n",
 635                        primary[i]->b_blocknr, gdbackups,
 636                        blk + primary[i]->b_blocknr); */
 637                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 638                 err2 = ext3_journal_dirty_metadata(handle, primary[i]);
 639                 if (!err)
 640                         err = err2;
 641         }
 642         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 643         ext3_mark_iloc_dirty(handle, inode, &iloc);
 644
 645 exit_bh:
 646         while (--res >= 0)
 647                 brelse(primary[res]);
 648         brelse(dind);
 649
 650 exit_free:
 651         kfree(primary);
 652
 653         return err;
 654 }
 655
 656 /*
 657  * Update the backup copies of the ext3 metadata.  These don't need to be part
 658  * of the main resize transaction, because e2fsck will re-write them if there
 659  * is a problem (basically only OOM will cause a problem).  However, we
 660  * _should_ update the backups if possible, in case the primary gets trashed
 661  * for some reason and we need to run e2fsck from a backup superblock.  The
 662  * important part is that the new block and inode counts are in the backup
 663  * superblocks, and the location of the new group metadata in the GDT backups.
 664  *
 665  * We do not need lock_super() for this, because these blocks are not
 666  * otherwise touched by the filesystem code when it is mounted.  We don't
 667  * need to worry about last changing from sbi->s_groups_count, because the
 668  * worst that can happen is that we do not copy the full number of backups
 669  * at this time.  The resize which changed s_groups_count will backup again.
 670  */
 671 static void update_backups(struct super_block *sb,
 672                            int blk_off, char *data, int size)
 673 {
 674         struct ext3_sb_info *sbi = EXT3_SB(sb);
 675         const unsigned long last = sbi->s_groups_count;
 676         const int bpg = EXT3_BLOCKS_PER_GROUP(sb);
 677         unsigned three = 1;
 678         unsigned five = 5;
 679         unsigned seven = 7;
 680         unsigned group;
 681         int rest = sb->s_blocksize - size;
 682         handle_t *handle;
 683         int err = 0, err2;
 684
 685         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 686         if (IS_ERR(handle)) {
 687                 group = 1;
 688                 err = PTR_ERR(handle);
 689                 goto exit_err;
 690         }
 691
 692         while ((group = ext3_list_backups(sb, &three, &five, &seven)) < last) {
 693                 struct buffer_head *bh;
 694
 695                 /* Out of journal space, and can't get more - abort - so sad */
 696                 if (handle->h_buffer_credits == 0 &&
 697                     ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA) &&
 698                     (err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA)))
 699                         break;
 700
 701                 bh = sb_getblk(sb, group * bpg + blk_off);
 702                 if (!bh) {
 703                         err = -EIO;
 704                         break;
 705                 }
 706                 ext3_debug("update metadata backup %#04lx\n",
 707                           (unsigned long)bh->b_blocknr);
 708                 if ((err = ext3_journal_get_write_access(handle, bh)))
 709                         break;
 710                 lock_buffer(bh);
 711                 memcpy(bh->b_data, data, size);
 712                 if (rest)
 713                         memset(bh->b_data + size, 0, rest);
 714                 set_buffer_uptodate(bh);
 715                 unlock_buffer(bh);
 716                 ext3_journal_dirty_metadata(handle, bh);
 717                 brelse(bh);
 718         }
 719         if ((err2 = ext3_journal_stop(handle)) && !err)
 720                 err = err2;
 721
 722         /*
 723          * Ugh! Need to have e2fsck write the backup copies.  It is too
 724          * late to revert the resize, we shouldn't fail just because of
 725          * the backup copies (they are only needed in case of corruption).
 726          *
 727          * However, if we got here we have a journal problem too, so we
 728          * can't really start a transaction to mark the superblock.
 729          * Chicken out and just set the flag on the hope it will be written
 730          * to disk, and if not - we will simply wait until next fsck.
 731          */
 732 exit_err:
 733         if (err) {
 734                 ext3_warning(sb, __FUNCTION__,
 735                              "can't update backup for group %d (err %d), "
 736                              "forcing fsck on next reboot", group, err);
 737                 sbi->s_mount_state &= ~EXT3_VALID_FS;
 738                 sbi->s_es->s_state &= cpu_to_le16(~EXT3_VALID_FS);
 739                 mark_buffer_dirty(sbi->s_sbh);
 740         }
 741 }
 742
 743 /* Add group descriptor data to an existing or new group descriptor block.
 744  * Ensure we handle all possible error conditions _before_ we start modifying
 745  * the filesystem, because we cannot abort the transaction and not have it
 746  * write the data to disk.
 747  *
 748  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 749  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 750  *
 751  * We only need to hold the superblock lock while we are actually adding
 752  * in the new group's counts to the superblock.  Prior to that we have
 753  * not really "added" the group at all.  We re-check that we are still
 754  * adding in the last group in case things have changed since verifying.
 755  */
 756 int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input)
 757 {
 758         struct ext3_sb_info *sbi = EXT3_SB(sb);
 759         struct ext3_super_block *es = sbi->s_es;
 760         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 761                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 762         struct buffer_head *primary = NULL;
 763         struct ext3_group_desc *gdp;
 764         struct inode *inode = NULL;
 765         handle_t *handle;
 766         int gdb_off, gdb_num;
 767         int err, err2;
 768
 769         gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 770         gdb_off = input->group % EXT3_DESC_PER_BLOCK(sb);
 771
 772         if (gdb_off == 0 && !EXT3_HAS_RO_COMPAT_FEATURE(sb,
 773                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 774                 ext3_warning(sb, __FUNCTION__,
 775                              "Can't resize non-sparse filesystem further");
 776                 return -EPERM;
 777         }
 778
 779         if (le32_to_cpu(es->s_blocks_count) + input->blocks_count <
 780             le32_to_cpu(es->s_blocks_count)) {
 781                 ext3_warning(sb, __FUNCTION__, "blocks_count overflow\n");
 782                 return -EINVAL;
 783         }
 784
 785         if (le32_to_cpu(es->s_inodes_count) + EXT3_INODES_PER_GROUP(sb) <
 786             le32_to_cpu(es->s_inodes_count)) {
 787                 ext3_warning(sb, __FUNCTION__, "inodes_count overflow\n");
 788                 return -EINVAL;
 789         }
 790
 791         if (reserved_gdb || gdb_off == 0) {
 792                 if (!EXT3_HAS_COMPAT_FEATURE(sb,
 793                                              EXT3_FEATURE_COMPAT_RESIZE_INODE)){
 794                         ext3_warning(sb, __FUNCTION__,
 795                                      "No reserved GDT blocks, can't resize");
 796                         return -EPERM;
 797                 }
 798                 inode = iget(sb, EXT3_RESIZE_INO);
 799                 if (!inode || is_bad_inode(inode)) {
 800                         ext3_warning(sb, __FUNCTION__,
 801                                      "Error opening resize inode");
 802                         iput(inode);
 803                         return -ENOENT;
 804                 }
 805         }
 806
 807         if ((err = verify_group_input(sb, input)))
 808                 goto exit_put;
 809
 810         if ((err = setup_new_group_blocks(sb, input)))
 811                 goto exit_put;
 812
 813         /*
 814          * We will always be modifying at least the superblock and a GDT
 815          * block.  If we are adding a group past the last current GDT block,
 816          * we will also modify the inode and the dindirect block.  If we
 817          * are adding a group with superblock/GDT backups  we will also
 818          * modify each of the reserved GDT dindirect blocks.
 819          */
 820         handle = ext3_journal_start_sb(sb,
 821                                        ext3_bg_has_super(sb, input->group) ?
 822                                        3 + reserved_gdb : 4);
 823         if (IS_ERR(handle)) {
 824                 err = PTR_ERR(handle);
 825                 goto exit_put;
 826         }
 827
 828         lock_super(sb);
 829         if (input->group != sbi->s_groups_count) {
 830                 ext3_warning(sb, __FUNCTION__,
 831                              "multiple resizers run on filesystem!");
 832                 err = -EBUSY;
 833                 goto exit_journal;
 834         }
 835
 836         if ((err = ext3_journal_get_write_access(handle, sbi->s_sbh)))
 837                 goto exit_journal;
 838
 839         /*
 840          * We will only either add reserved group blocks to a backup group
 841          * or remove reserved blocks for the first group in a new group block.
 842          * Doing both would be mean more complex code, and sane people don't
 843          * use non-sparse filesystems anymore.  This is already checked above.
 844          */
 845         if (gdb_off) {
 846                 primary = sbi->s_group_desc[gdb_num];
 847                 if ((err = ext3_journal_get_write_access(handle, primary)))
 848                         goto exit_journal;
 849
 850                 if (reserved_gdb && ext3_bg_num_gdb(sb, input->group) &&
 851                     (err = reserve_backup_gdb(handle, inode, input)))
 852                         goto exit_journal;
 853         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 854                 goto exit_journal;
 855
 856         /*
 857          * OK, now we've set up the new group.  Time to make it active.
 858          *
 859          * Current kernels don't lock all allocations via lock_super(),
 860          * so we have to be safe wrt. concurrent accesses the group
 861          * data.  So we need to be careful to set all of the relevant
 862          * group descriptor data etc. *before* we enable the group.
 863          *
 864          * The key field here is sbi->s_groups_count: as long as
 865          * that retains its old value, nobody is going to access the new
 866          * group.
 867          *
 868          * So first we update all the descriptor metadata for the new
 869          * group; then we update the total disk blocks count; then we
 870          * update the groups count to enable the group; then finally we
 871          * update the free space counts so that the system can start
 872          * using the new disk blocks.
 873          */
 874
 875         /* Update group descriptor block for new group */
 876         gdp = (struct ext3_group_desc *)primary->b_data + gdb_off;
 877
 878         gdp->bg_block_bitmap = cpu_to_le32(input->block_bitmap);
 879         gdp->bg_inode_bitmap = cpu_to_le32(input->inode_bitmap);
 880         gdp->bg_inode_table = cpu_to_le32(input->inode_table);
 881         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 882         gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
 883
 884         /*
 885          * Make the new blocks and inodes valid next.  We do this before
 886          * increasing the group count so that once the group is enabled,
 887          * all of its blocks and inodes are already valid.
 888          *
 889          * We always allocate group-by-group, then block-by-block or
 890          * inode-by-inode within a group, so enabling these
 891          * blocks/inodes before the group is live won't actually let us
 892          * allocate the new space yet.
 893          */
 894         es->s_blocks_count = cpu_to_le32(le32_to_cpu(es->s_blocks_count) +
 895                 input->blocks_count);
 896         es->s_inodes_count = cpu_to_le32(le32_to_cpu(es->s_inodes_count) +
 897                 EXT3_INODES_PER_GROUP(sb));
 898
 899         /*
 900          * We need to protect s_groups_count against other CPUs seeing
 901          * inconsistent state in the superblock.
 902          *
 903          * The precise rules we use are:
 904          *
 905          * * Writers of s_groups_count *must* hold lock_super
 906          * AND
 907          * * Writers must perform a smp_wmb() after updating all dependent
 908          *   data and before modifying the groups count
 909          *
 910          * * Readers must hold lock_super() over the access
 911          * OR
 912          * * Readers must perform an smp_rmb() after reading the groups count
 913          *   and before reading any dependent data.
 914          *
 915          * NB. These rules can be relaxed when checking the group count
 916          * while freeing data, as we can only allocate from a block
 917          * group after serialising against the group count, and we can
 918          * only then free after serialising in turn against that
 919          * allocation.
 920          */
 921         smp_wmb();
 922
 923         /* Update the global fs size fields */
 924         sbi->s_groups_count++;
 925
 926         ext3_journal_dirty_metadata(handle, primary);
 927
 928         /* Update the reserved block counts only once the new group is
 929          * active. */
 930         es->s_r_blocks_count = cpu_to_le32(le32_to_cpu(es->s_r_blocks_count) +
 931                 input->reserved_blocks);
 932
 933         /* Update the free space counts */
 934         percpu_counter_add(&sbi->s_freeblocks_counter,
 935                            input->free_blocks_count);
 936         percpu_counter_add(&sbi->s_freeinodes_counter,
 937                            EXT3_INODES_PER_GROUP(sb));
 938
 939         ext3_journal_dirty_metadata(handle, sbi->s_sbh);
 940         sb->s_dirt = 1;
 941
 942 exit_journal:
 943         unlock_super(sb);
 944         if ((err2 = ext3_journal_stop(handle)) && !err)
 945                 err = err2;
 946         if (!err) {
 947                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 948                                sizeof(struct ext3_super_block));
 949                 update_backups(sb, primary->b_blocknr, primary->b_data,
 950                                primary->b_size);
 951         }
 952 exit_put:
 953         iput(inode);
 954         return err;
 955 } /* ext3_group_add */
 956
 957 /* Extend the filesystem to the new number of blocks specified.  This entry
 958  * point is only used to extend the current filesystem to the end of the last
 959  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 960  * for emergencies (because it has no dependencies on reserved blocks).
 961  *
 962  * If we _really_ wanted, we could use default values to call ext3_group_add()
 963  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 964  * GDT blocks are reserved to grow to the desired size.
 965  */
 966 int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es,
 967                       ext3_fsblk_t n_blocks_count)
 968 {
 969         ext3_fsblk_t o_blocks_count;
 970         unsigned long o_groups_count;
 971         ext3_grpblk_t last;
 972         ext3_grpblk_t add;
 973         struct buffer_head * bh;
 974         handle_t *handle;
 975         int err;
 976         unsigned long freed_blocks;
 977
 978         /* We don't need to worry about locking wrt other resizers just
 979          * yet: we're going to revalidate es->s_blocks_count after
 980          * taking lock_super() below. */
 981         o_blocks_count = le32_to_cpu(es->s_blocks_count);
 982         o_groups_count = EXT3_SB(sb)->s_groups_count;
 983
 984         if (test_opt(sb, DEBUG))
 985                 printk(KERN_DEBUG "EXT3-fs: extending last group from "E3FSBLK" uto "E3FSBLK" blocks\n",
 986                        o_blocks_count, n_blocks_count);
 987
 988         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 989                 return 0;
 990
 991         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
 992                 printk(KERN_ERR "EXT3-fs: filesystem on %s:"
 993                         " too large to resize to %lu blocks safely\n",
 994                         sb->s_id, n_blocks_count);
 995                 if (sizeof(sector_t) < 8)
 996                         ext3_warning(sb, __FUNCTION__,
 997                         "CONFIG_LBD not enabled\n");
 998                 return -EINVAL;
 999         }
1000
1001         if (n_blocks_count < o_blocks_count) {
1002                 ext3_warning(sb, __FUNCTION__,
1003                              "can't shrink FS - resize aborted");
1004                 return -EBUSY;
1005         }
1006
1007         /* Handle the remaining blocks in the last group only. */
1008         last = (o_blocks_count - le32_to_cpu(es->s_first_data_block)) %
1009                 EXT3_BLOCKS_PER_GROUP(sb);
1010
1011         if (last == 0) {
1012                 ext3_warning(sb, __FUNCTION__,
1013                              "need to use ext2online to resize further");
1014                 return -EPERM;
1015         }
1016
1017         add = EXT3_BLOCKS_PER_GROUP(sb) - last;
1018
1019         if (o_blocks_count + add < o_blocks_count) {
1020                 ext3_warning(sb, __FUNCTION__, "blocks_count overflow");
1021                 return -EINVAL;
1022         }
1023
1024         if (o_blocks_count + add > n_blocks_count)
1025                 add = n_blocks_count - o_blocks_count;
1026
1027         if (o_blocks_count + add < n_blocks_count)
1028                 ext3_warning(sb, __FUNCTION__,
1029                              "will only finish group ("E3FSBLK
1030                              " blocks, %u new)",
1031                              o_blocks_count + add, add);
1032
1033         /* See if the device is actually as big as what was requested */
1034         bh = sb_bread(sb, o_blocks_count + add -1);
1035         if (!bh) {
1036                 ext3_warning(sb, __FUNCTION__,
1037                              "can't read last block, resize aborted");
1038                 return -ENOSPC;
1039         }
1040         brelse(bh);
1041
1042         /* We will update the superblock, one block bitmap, and
1043          * one group descriptor via ext3_free_blocks().
1044          */
1045         handle = ext3_journal_start_sb(sb, 3);
1046         if (IS_ERR(handle)) {
1047                 err = PTR_ERR(handle);
1048                 ext3_warning(sb, __FUNCTION__, "error %d on journal start",err);
1049                 goto exit_put;
1050         }
1051
1052         lock_super(sb);
1053         if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
1054                 ext3_warning(sb, __FUNCTION__,
1055                              "multiple resizers run on filesystem!");
1056                 unlock_super(sb);
1057                 err = -EBUSY;
1058                 goto exit_put;
1059         }
1060
1061         if ((err = ext3_journal_get_write_access(handle,
1062                                                  EXT3_SB(sb)->s_sbh))) {
1063                 ext3_warning(sb, __FUNCTION__,
1064                              "error %d on journal write access", err);
1065                 unlock_super(sb);
1066                 ext3_journal_stop(handle);
1067                 goto exit_put;
1068         }
1069         es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
1070         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
1071         sb->s_dirt = 1;
1072         unlock_super(sb);
1073         ext3_debug("freeing blocks %lu through "E3FSBLK"\n", o_blocks_count,
1074                    o_blocks_count + add);
1075         ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1076         ext3_debug("freed blocks "E3FSBLK" through "E3FSBLK"\n", o_blocks_count,
1077                    o_blocks_count + add);
1078         if ((err = ext3_journal_stop(handle)))
1079                 goto exit_put;
1080         if (test_opt(sb, DEBUG))
1081                 printk(KERN_DEBUG "EXT3-fs: extended group to %u blocks\n",
1082                        le32_to_cpu(es->s_blocks_count));
1083         update_backups(sb, EXT3_SB(sb)->s_sbh->b_blocknr, (char *)es,
1084                        sizeof(struct ext3_super_block));
1085 exit_put:
1086         return err;
1087 } /* ext3_group_extend */