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