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