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 #include <linux/config.h>
  12
  13 #define EXT3FS_DEBUG
  14
  15 #include <linux/sched.h>
  16 #include <linux/smp_lock.h>
  17 #include <linux/ext3_jbd.h>
  18
  19 #include <linux/errno.h>
  20 #include <linux/slab.h>
  21
  22
  23 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  24 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  25
  26 static int verify_group_input(struct super_block *sb,
  27                               struct ext3_new_group_data *input)
  28 {
  29         struct ext3_sb_info *sbi = EXT3_SB(sb);
  30         struct ext3_super_block *es = sbi->s_es;
  31         unsigned start = le32_to_cpu(es->s_blocks_count);
  32         unsigned end = start + input->blocks_count;
  33         unsigned group = input->group;
  34         unsigned itend = input->inode_table + sbi->s_itb_per_group;
  35         unsigned overhead = ext3_bg_has_super(sb, group) ?
  36                 (1 + ext3_bg_num_gdb(sb, group) +
  37                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  38         unsigned metaend = start + overhead;
  39         struct buffer_head *bh = NULL;
  40         int free_blocks_count;
  41         int err = -EINVAL;
  42
  43         input->free_blocks_count = free_blocks_count =
  44                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  45
  46         if (test_opt(sb, DEBUG))
  47                 printk(KERN_DEBUG "EXT3-fs: adding %s group %u: %u blocks "
  48                        "(%d free, %u reserved)\n",
  49                        ext3_bg_has_super(sb, input->group) ? "normal" :
  50                        "no-super", input->group, input->blocks_count,
  51                        free_blocks_count, input->reserved_blocks);
  52
  53         if (group != sbi->s_groups_count)
  54                 ext3_warning(sb, __FUNCTION__,
  55                              "Cannot add at group %u (only %lu groups)",
  56                              input->group, sbi->s_groups_count);
  57         else if ((start - le32_to_cpu(es->s_first_data_block)) %
  58                  EXT3_BLOCKS_PER_GROUP(sb))
  59                 ext3_warning(sb, __FUNCTION__, "Last group not full");
  60         else if (input->reserved_blocks > input->blocks_count / 5)
  61                 ext3_warning(sb, __FUNCTION__, "Reserved blocks too high (%u)",
  62                              input->reserved_blocks);
  63         else if (free_blocks_count < 0)
  64                 ext3_warning(sb, __FUNCTION__, "Bad blocks count %u",
  65                              input->blocks_count);
  66         else if (!(bh = sb_bread(sb, end - 1)))
  67                 ext3_warning(sb, __FUNCTION__, "Cannot read last block (%u)",
  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-%u)",
  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-%u)",
  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-%u)",
  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 (%u-%u)",
  97                              input->block_bitmap, start, metaend - 1);
  98         else if (inside(input->inode_bitmap, start, metaend))
  99                 ext3_warning(sb, __FUNCTION__,
 100                              "Inode bitmap (%u) in GDT table (%u-%u)",
 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-%u) overlaps GDT table (%u-%u)",
 106                              input->inode_table, itend - 1, start, metaend - 1);
 107         else
 108                 err = 0;
 109         brelse(bh);
 110
 111         return err;
 112 }
 113
 114 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 115                                   unsigned long blk)
 116 {
 117         struct buffer_head *bh;
 118         int err;
 119
 120         bh = sb_getblk(sb, blk);
 121         if (!bh)
 122                 return ERR_PTR(-EIO);
 123         if ((err = ext3_journal_get_write_access(handle, bh))) {
 124                 brelse(bh);
 125                 bh = ERR_PTR(err);
 126         } else {
 127                 lock_buffer(bh);
 128                 memset(bh->b_data, 0, sb->s_blocksize);
 129                 set_buffer_uptodate(bh);
 130                 unlock_buffer(bh);
 131         }
 132
 133         return bh;
 134 }
 135
 136 /*
 137  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 138  * need to use it within a single byte (to ensure we get endianness right).
 139  * We can use memset for the rest of the bitmap as there are no other users.
 140  */
 141 static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 142 {
 143         int i;
 144
 145         if (start_bit >= end_bit)
 146                 return;
 147
 148         ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 149         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 150                 ext3_set_bit(i, bitmap);
 151         if (i < end_bit)
 152                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 153 }
 154
 155 /*
 156  * Set up the block and inode bitmaps, and the inode table for the new group.
 157  * This doesn't need to be part of the main transaction, since we are only
 158  * changing blocks outside the actual filesystem.  We still do journaling to
 159  * ensure the recovery is correct in case of a failure just after resize.
 160  * If any part of this fails, we simply abort the resize.
 161  */
 162 static int setup_new_group_blocks(struct super_block *sb,
 163                                   struct ext3_new_group_data *input)
 164 {
 165         struct ext3_sb_info *sbi = EXT3_SB(sb);
 166         unsigned long start = input->group * sbi->s_blocks_per_group +
 167                 le32_to_cpu(sbi->s_es->s_first_data_block);
 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         unsigned long block;
 174         int 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], 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 unsigned long 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         __u32 *p = (__u32 *)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 %ld missing grp %d (%ld)",
 344                                      blk, grp,
 345                                      grp * EXT3_BLOCKS_PER_GROUP(sb) + blk);
 346                         return -EINVAL;
 347                 }
 348                 if (++gdbackups > EXT3_ADDR_PER_BLOCK(sb))
 349                         return -EFBIG;
 350         }
 351
 352         return gdbackups;
 353 }
 354
 355 /*
 356  * Called when we need to bring a reserved group descriptor table block into
 357  * use from the resize inode.  The primary copy of the new GDT block currently
 358  * is an indirect block (under the double indirect block in the resize inode).
 359  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 360  * block, in group order.  Even though we know all the block numbers we need,
 361  * we check to ensure that the resize inode has actually reserved these blocks.
 362  *
 363  * Don't need to update the block bitmaps because the blocks are still in use.
 364  *
 365  * We get all of the error cases out of the way, so that we are sure to not
 366  * fail once we start modifying the data on disk, because JBD has no rollback.
 367  */
 368 static int add_new_gdb(handle_t *handle, struct inode *inode,
 369                        struct ext3_new_group_data *input,
 370                        struct buffer_head **primary)
 371 {
 372         struct super_block *sb = inode->i_sb;
 373         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
 374         unsigned long gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 375         unsigned long gdblock = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 376         struct buffer_head **o_group_desc, **n_group_desc;
 377         struct buffer_head *dind;
 378         int gdbackups;
 379         struct ext3_iloc iloc;
 380         __u32 *data;
 381         int err;
 382
 383         if (test_opt(sb, DEBUG))
 384                 printk(KERN_DEBUG
 385                        "EXT3-fs: ext3_add_new_gdb: adding group block %lu\n",
 386                        gdb_num);
 387
 388         /*
 389          * If we are not using the primary superblock/GDT copy don't resize,
 390          * because the user tools have no way of handling this.  Probably a
 391          * bad time to do it anyways.
 392          */
 393         if (EXT3_SB(sb)->s_sbh->b_blocknr !=
 394             le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) {
 395                 ext3_warning(sb, __FUNCTION__,
 396                         "won't resize using backup superblock at %llu",
 397                         (unsigned long long)EXT3_SB(sb)->s_sbh->b_blocknr);
 398                 return -EPERM;
 399         }
 400
 401         *primary = sb_bread(sb, gdblock);
 402         if (!*primary)
 403                 return -EIO;
 404
 405         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 406                 err = gdbackups;
 407                 goto exit_bh;
 408         }
 409
 410         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 411         dind = sb_bread(sb, le32_to_cpu(*data));
 412         if (!dind) {
 413                 err = -EIO;
 414                 goto exit_bh;
 415         }
 416
 417         data = (__u32 *)dind->b_data;
 418         if (le32_to_cpu(data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)]) != gdblock) {
 419                 ext3_warning(sb, __FUNCTION__,
 420                              "new group %u GDT block %lu not reserved",
 421                              input->group, gdblock);
 422                 err = -EINVAL;
 423                 goto exit_dind;
 424         }
 425
 426         if ((err = ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh)))
 427                 goto exit_dind;
 428
 429         if ((err = ext3_journal_get_write_access(handle, *primary)))
 430                 goto exit_sbh;
 431
 432         if ((err = ext3_journal_get_write_access(handle, dind)))
 433                 goto exit_primary;
 434
 435         /* ext3_reserve_inode_write() gets a reference on the iloc */
 436         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 437                 goto exit_dindj;
 438
 439         n_group_desc = (struct buffer_head **)kmalloc((gdb_num + 1) *
 440                                 sizeof(struct buffer_head *), GFP_KERNEL);
 441         if (!n_group_desc) {
 442                 err = -ENOMEM;
 443                 ext3_warning (sb, __FUNCTION__,
 444                               "not enough memory for %lu groups", gdb_num + 1);
 445                 goto exit_inode;
 446         }
 447
 448         /*
 449          * Finally, we have all of the possible failures behind us...
 450          *
 451          * Remove new GDT block from inode double-indirect block and clear out
 452          * the new GDT block for use (which also "frees" the backup GDT blocks
 453          * from the reserved inode).  We don't need to change the bitmaps for
 454          * these blocks, because they are marked as in-use from being in the
 455          * reserved inode, and will become GDT blocks (primary and backup).
 456          */
 457         data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)] = 0;
 458         ext3_journal_dirty_metadata(handle, dind);
 459         brelse(dind);
 460         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 461         ext3_mark_iloc_dirty(handle, inode, &iloc);
 462         memset((*primary)->b_data, 0, sb->s_blocksize);
 463         ext3_journal_dirty_metadata(handle, *primary);
 464
 465         o_group_desc = EXT3_SB(sb)->s_group_desc;
 466         memcpy(n_group_desc, o_group_desc,
 467                EXT3_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 468         n_group_desc[gdb_num] = *primary;
 469         EXT3_SB(sb)->s_group_desc = n_group_desc;
 470         EXT3_SB(sb)->s_gdb_count++;
 471         kfree(o_group_desc);
 472
 473         es->s_reserved_gdt_blocks =
 474                 cpu_to_le16(le16_to_cpu(es->s_reserved_gdt_blocks) - 1);
 475         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 476
 477         return 0;
 478
 479 exit_inode:
 480         //ext3_journal_release_buffer(handle, iloc.bh);
 481         brelse(iloc.bh);
 482 exit_dindj:
 483         //ext3_journal_release_buffer(handle, dind);
 484 exit_primary:
 485         //ext3_journal_release_buffer(handle, *primary);
 486 exit_sbh:
 487         //ext3_journal_release_buffer(handle, *primary);
 488 exit_dind:
 489         brelse(dind);
 490 exit_bh:
 491         brelse(*primary);
 492
 493         ext3_debug("leaving with error %d\n", err);
 494         return err;
 495 }
 496
 497 /*
 498  * Called when we are adding a new group which has a backup copy of each of
 499  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 500  * We need to add these reserved backup GDT blocks to the resize inode, so
 501  * that they are kept for future resizing and not allocated to files.
 502  *
 503  * Each reserved backup GDT block will go into a different indirect block.
 504  * The indirect blocks are actually the primary reserved GDT blocks,
 505  * so we know in advance what their block numbers are.  We only get the
 506  * double-indirect block to verify it is pointing to the primary reserved
 507  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 508  * backup GDT blocks are stored in their reserved primary GDT block.
 509  */
 510 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 511                               struct ext3_new_group_data *input)
 512 {
 513         struct super_block *sb = inode->i_sb;
 514         int reserved_gdb =le16_to_cpu(EXT3_SB(sb)->s_es->s_reserved_gdt_blocks);
 515         struct buffer_head **primary;
 516         struct buffer_head *dind;
 517         struct ext3_iloc iloc;
 518         unsigned long blk;
 519         __u32 *data, *end;
 520         int gdbackups = 0;
 521         int res, i;
 522         int err;
 523
 524         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_KERNEL);
 525         if (!primary)
 526                 return -ENOMEM;
 527
 528         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 529         dind = sb_bread(sb, le32_to_cpu(*data));
 530         if (!dind) {
 531                 err = -EIO;
 532                 goto exit_free;
 533         }
 534
 535         blk = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + EXT3_SB(sb)->s_gdb_count;
 536         data = (__u32 *)dind->b_data + EXT3_SB(sb)->s_gdb_count;
 537         end = (__u32 *)dind->b_data + EXT3_ADDR_PER_BLOCK(sb);
 538
 539         /* Get each reserved primary GDT block and verify it holds backups */
 540         for (res = 0; res < reserved_gdb; res++, blk++) {
 541                 if (le32_to_cpu(*data) != blk) {
 542                         ext3_warning(sb, __FUNCTION__,
 543                                      "reserved block %lu not at offset %ld",
 544                                      blk, (long)(data - (__u32 *)dind->b_data));
 545                         err = -EINVAL;
 546                         goto exit_bh;
 547                 }
 548                 primary[res] = sb_bread(sb, blk);
 549                 if (!primary[res]) {
 550                         err = -EIO;
 551                         goto exit_bh;
 552                 }
 553                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 554                         brelse(primary[res]);
 555                         err = gdbackups;
 556                         goto exit_bh;
 557                 }
 558                 if (++data >= end)
 559                         data = (__u32 *)dind->b_data;
 560         }
 561
 562         for (i = 0; i < reserved_gdb; i++) {
 563                 if ((err = ext3_journal_get_write_access(handle, primary[i]))) {
 564                         /*
 565                         int j;
 566                         for (j = 0; j < i; j++)
 567                                 ext3_journal_release_buffer(handle, primary[j]);
 568                          */
 569                         goto exit_bh;
 570                 }
 571         }
 572
 573         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 574                 goto exit_bh;
 575
 576         /*
 577          * Finally we can add each of the reserved backup GDT blocks from
 578          * the new group to its reserved primary GDT block.
 579          */
 580         blk = input->group * EXT3_BLOCKS_PER_GROUP(sb);
 581         for (i = 0; i < reserved_gdb; i++) {
 582                 int err2;
 583                 data = (__u32 *)primary[i]->b_data;
 584                 /* printk("reserving backup %lu[%u] = %lu\n",
 585                        primary[i]->b_blocknr, gdbackups,
 586                        blk + primary[i]->b_blocknr); */
 587                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 588                 err2 = ext3_journal_dirty_metadata(handle, primary[i]);
 589                 if (!err)
 590                         err = err2;
 591         }
 592         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 593         ext3_mark_iloc_dirty(handle, inode, &iloc);
 594
 595 exit_bh:
 596         while (--res >= 0)
 597                 brelse(primary[res]);
 598         brelse(dind);
 599
 600 exit_free:
 601         kfree(primary);
 602
 603         return err;
 604 }
 605
 606 /*
 607  * Update the backup copies of the ext3 metadata.  These don't need to be part
 608  * of the main resize transaction, because e2fsck will re-write them if there
 609  * is a problem (basically only OOM will cause a problem).  However, we
 610  * _should_ update the backups if possible, in case the primary gets trashed
 611  * for some reason and we need to run e2fsck from a backup superblock.  The
 612  * important part is that the new block and inode counts are in the backup
 613  * superblocks, and the location of the new group metadata in the GDT backups.
 614  *
 615  * We do not need lock_super() for this, because these blocks are not
 616  * otherwise touched by the filesystem code when it is mounted.  We don't
 617  * need to worry about last changing from sbi->s_groups_count, because the
 618  * worst that can happen is that we do not copy the full number of backups
 619  * at this time.  The resize which changed s_groups_count will backup again.
 620  */
 621 static void update_backups(struct super_block *sb,
 622                            int blk_off, char *data, int size)
 623 {
 624         struct ext3_sb_info *sbi = EXT3_SB(sb);
 625         const unsigned long last = sbi->s_groups_count;
 626         const int bpg = EXT3_BLOCKS_PER_GROUP(sb);
 627         unsigned three = 1;
 628         unsigned five = 5;
 629         unsigned seven = 7;
 630         unsigned group;
 631         int rest = sb->s_blocksize - size;
 632         handle_t *handle;
 633         int err = 0, err2;
 634
 635         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 636         if (IS_ERR(handle)) {
 637                 group = 1;
 638                 err = PTR_ERR(handle);
 639                 goto exit_err;
 640         }
 641
 642         while ((group = ext3_list_backups(sb, &three, &five, &seven)) < last) {
 643                 struct buffer_head *bh;
 644
 645                 /* Out of journal space, and can't get more - abort - so sad */
 646                 if (handle->h_buffer_credits == 0 &&
 647                     ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA) &&
 648                     (err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA)))
 649                         break;
 650
 651                 bh = sb_getblk(sb, group * bpg + blk_off);
 652                 if (!bh) {
 653                         err = -EIO;
 654                         break;
 655                 }
 656                 ext3_debug("update metadata backup %#04lx\n",
 657                           (unsigned long)bh->b_blocknr);
 658                 if ((err = ext3_journal_get_write_access(handle, bh)))
 659                         break;
 660                 lock_buffer(bh);
 661                 memcpy(bh->b_data, data, size);
 662                 if (rest)
 663                         memset(bh->b_data + size, 0, rest);
 664                 set_buffer_uptodate(bh);
 665                 unlock_buffer(bh);
 666                 ext3_journal_dirty_metadata(handle, bh);
 667                 brelse(bh);
 668         }
 669         if ((err2 = ext3_journal_stop(handle)) && !err)
 670                 err = err2;
 671
 672         /*
 673          * Ugh! Need to have e2fsck write the backup copies.  It is too
 674          * late to revert the resize, we shouldn't fail just because of
 675          * the backup copies (they are only needed in case of corruption).
 676          *
 677          * However, if we got here we have a journal problem too, so we
 678          * can't really start a transaction to mark the superblock.
 679          * Chicken out and just set the flag on the hope it will be written
 680          * to disk, and if not - we will simply wait until next fsck.
 681          */
 682 exit_err:
 683         if (err) {
 684                 ext3_warning(sb, __FUNCTION__,
 685                              "can't update backup for group %d (err %d), "
 686                              "forcing fsck on next reboot", group, err);
 687                 sbi->s_mount_state &= ~EXT3_VALID_FS;
 688                 sbi->s_es->s_state &= ~cpu_to_le16(EXT3_VALID_FS);
 689                 mark_buffer_dirty(sbi->s_sbh);
 690         }
 691 }
 692
 693 /* Add group descriptor data to an existing or new group descriptor block.
 694  * Ensure we handle all possible error conditions _before_ we start modifying
 695  * the filesystem, because we cannot abort the transaction and not have it
 696  * write the data to disk.
 697  *
 698  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 699  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 700  *
 701  * We only need to hold the superblock lock while we are actually adding
 702  * in the new group's counts to the superblock.  Prior to that we have
 703  * not really "added" the group at all.  We re-check that we are still
 704  * adding in the last group in case things have changed since verifying.
 705  */
 706 int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input)
 707 {
 708         struct ext3_sb_info *sbi = EXT3_SB(sb);
 709         struct ext3_super_block *es = sbi->s_es;
 710         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 711                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 712         struct buffer_head *primary = NULL;
 713         struct ext3_group_desc *gdp;
 714         struct inode *inode = NULL;
 715         handle_t *handle;
 716         int gdb_off, gdb_num;
 717         int err, err2;
 718
 719         gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 720         gdb_off = input->group % EXT3_DESC_PER_BLOCK(sb);
 721
 722         if (gdb_off == 0 && !EXT3_HAS_RO_COMPAT_FEATURE(sb,
 723                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 724                 ext3_warning(sb, __FUNCTION__,
 725                              "Can't resize non-sparse filesystem further");
 726                 return -EPERM;
 727         }
 728
 729         if (reserved_gdb || gdb_off == 0) {
 730                 if (!EXT3_HAS_COMPAT_FEATURE(sb,
 731                                              EXT3_FEATURE_COMPAT_RESIZE_INODE)){
 732                         ext3_warning(sb, __FUNCTION__,
 733                                      "No reserved GDT blocks, can't resize");
 734                         return -EPERM;
 735                 }
 736                 inode = iget(sb, EXT3_RESIZE_INO);
 737                 if (!inode || is_bad_inode(inode)) {
 738                         ext3_warning(sb, __FUNCTION__,
 739                                      "Error opening resize inode");
 740                         iput(inode);
 741                         return -ENOENT;
 742                 }
 743         }
 744
 745         if ((err = verify_group_input(sb, input)))
 746                 goto exit_put;
 747
 748         if ((err = setup_new_group_blocks(sb, input)))
 749                 goto exit_put;
 750
 751         /*
 752          * We will always be modifying at least the superblock and a GDT
 753          * block.  If we are adding a group past the last current GDT block,
 754          * we will also modify the inode and the dindirect block.  If we
 755          * are adding a group with superblock/GDT backups  we will also
 756          * modify each of the reserved GDT dindirect blocks.
 757          */
 758         handle = ext3_journal_start_sb(sb,
 759                                        ext3_bg_has_super(sb, input->group) ?
 760                                        3 + reserved_gdb : 4);
 761         if (IS_ERR(handle)) {
 762                 err = PTR_ERR(handle);
 763                 goto exit_put;
 764         }
 765
 766         lock_super(sb);
 767         if (input->group != sbi->s_groups_count) {
 768                 ext3_warning(sb, __FUNCTION__,
 769                              "multiple resizers run on filesystem!");
 770                 err = -EBUSY;
 771                 goto exit_journal;
 772         }
 773
 774         if ((err = ext3_journal_get_write_access(handle, sbi->s_sbh)))
 775                 goto exit_journal;
 776
 777         /*
 778          * We will only either add reserved group blocks to a backup group
 779          * or remove reserved blocks for the first group in a new group block.
 780          * Doing both would be mean more complex code, and sane people don't
 781          * use non-sparse filesystems anymore.  This is already checked above.
 782          */
 783         if (gdb_off) {
 784                 primary = sbi->s_group_desc[gdb_num];
 785                 if ((err = ext3_journal_get_write_access(handle, primary)))
 786                         goto exit_journal;
 787
 788                 if (reserved_gdb && ext3_bg_num_gdb(sb, input->group) &&
 789                     (err = reserve_backup_gdb(handle, inode, input)))
 790                         goto exit_journal;
 791         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 792                 goto exit_journal;
 793
 794         /*
 795          * OK, now we've set up the new group.  Time to make it active.
 796          *
 797          * Current kernels don't lock all allocations via lock_super(),
 798          * so we have to be safe wrt. concurrent accesses the group
 799          * data.  So we need to be careful to set all of the relevant
 800          * group descriptor data etc. *before* we enable the group.
 801          *
 802          * The key field here is sbi->s_groups_count: as long as
 803          * that retains its old value, nobody is going to access the new
 804          * group.
 805          *
 806          * So first we update all the descriptor metadata for the new
 807          * group; then we update the total disk blocks count; then we
 808          * update the groups count to enable the group; then finally we
 809          * update the free space counts so that the system can start
 810          * using the new disk blocks.
 811          */
 812
 813         /* Update group descriptor block for new group */
 814         gdp = (struct ext3_group_desc *)primary->b_data + gdb_off;
 815
 816         gdp->bg_block_bitmap = cpu_to_le32(input->block_bitmap);
 817         gdp->bg_inode_bitmap = cpu_to_le32(input->inode_bitmap);
 818         gdp->bg_inode_table = cpu_to_le32(input->inode_table);
 819         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 820         gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
 821
 822         /*
 823          * Make the new blocks and inodes valid next.  We do this before
 824          * increasing the group count so that once the group is enabled,
 825          * all of its blocks and inodes are already valid.
 826          *
 827          * We always allocate group-by-group, then block-by-block or
 828          * inode-by-inode within a group, so enabling these
 829          * blocks/inodes before the group is live won't actually let us
 830          * allocate the new space yet.
 831          */
 832         es->s_blocks_count = cpu_to_le32(le32_to_cpu(es->s_blocks_count) +
 833                 input->blocks_count);
 834         es->s_inodes_count = cpu_to_le32(le32_to_cpu(es->s_inodes_count) +
 835                 EXT3_INODES_PER_GROUP(sb));
 836
 837         /*
 838          * We need to protect s_groups_count against other CPUs seeing
 839          * inconsistent state in the superblock.
 840          *
 841          * The precise rules we use are:
 842          *
 843          * * Writers of s_groups_count *must* hold lock_super
 844          * AND
 845          * * Writers must perform a smp_wmb() after updating all dependent
 846          *   data and before modifying the groups count
 847          *
 848          * * Readers must hold lock_super() over the access
 849          * OR
 850          * * Readers must perform an smp_rmb() after reading the groups count
 851          *   and before reading any dependent data.
 852          *
 853          * NB. These rules can be relaxed when checking the group count
 854          * while freeing data, as we can only allocate from a block
 855          * group after serialising against the group count, and we can
 856          * only then free after serialising in turn against that
 857          * allocation.
 858          */
 859         smp_wmb();
 860
 861         /* Update the global fs size fields */
 862         sbi->s_groups_count++;
 863
 864         ext3_journal_dirty_metadata(handle, primary);
 865
 866         /* Update the reserved block counts only once the new group is
 867          * active. */
 868         es->s_r_blocks_count = cpu_to_le32(le32_to_cpu(es->s_r_blocks_count) +
 869                 input->reserved_blocks);
 870
 871         /* Update the free space counts */
 872         percpu_counter_mod(&sbi->s_freeblocks_counter,
 873                            input->free_blocks_count);
 874         percpu_counter_mod(&sbi->s_freeinodes_counter,
 875                            EXT3_INODES_PER_GROUP(sb));
 876
 877         ext3_journal_dirty_metadata(handle, sbi->s_sbh);
 878         sb->s_dirt = 1;
 879
 880 exit_journal:
 881         unlock_super(sb);
 882         if ((err2 = ext3_journal_stop(handle)) && !err)
 883                 err = err2;
 884         if (!err) {
 885                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 886                                sizeof(struct ext3_super_block));
 887                 update_backups(sb, primary->b_blocknr, primary->b_data,
 888                                primary->b_size);
 889         }
 890 exit_put:
 891         iput(inode);
 892         return err;
 893 } /* ext3_group_add */
 894
 895 /* Extend the filesystem to the new number of blocks specified.  This entry
 896  * point is only used to extend the current filesystem to the end of the last
 897  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 898  * for emergencies (because it has no dependencies on reserved blocks).
 899  *
 900  * If we _really_ wanted, we could use default values to call ext3_group_add()
 901  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 902  * GDT blocks are reserved to grow to the desired size.
 903  */
 904 int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es,
 905                       unsigned long n_blocks_count)
 906 {
 907         unsigned long o_blocks_count;
 908         unsigned long o_groups_count;
 909         unsigned long last;
 910         int add;
 911         struct buffer_head * bh;
 912         handle_t *handle;
 913         int err, freed_blocks;
 914
 915         /* We don't need to worry about locking wrt other resizers just
 916          * yet: we're going to revalidate es->s_blocks_count after
 917          * taking lock_super() below. */
 918         o_blocks_count = le32_to_cpu(es->s_blocks_count);
 919         o_groups_count = EXT3_SB(sb)->s_groups_count;
 920
 921         if (test_opt(sb, DEBUG))
 922                 printk(KERN_DEBUG "EXT3-fs: extending last group from %lu to %lu blocks\n",
 923                        o_blocks_count, n_blocks_count);
 924
 925         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 926                 return 0;
 927
 928         if (n_blocks_count < o_blocks_count) {
 929                 ext3_warning(sb, __FUNCTION__,
 930                              "can't shrink FS - resize aborted");
 931                 return -EBUSY;
 932         }
 933
 934         /* Handle the remaining blocks in the last group only. */
 935         last = (o_blocks_count - le32_to_cpu(es->s_first_data_block)) %
 936                 EXT3_BLOCKS_PER_GROUP(sb);
 937
 938         if (last == 0) {
 939                 ext3_warning(sb, __FUNCTION__,
 940                              "need to use ext2online to resize further");
 941                 return -EPERM;
 942         }
 943
 944         add = EXT3_BLOCKS_PER_GROUP(sb) - last;
 945
 946         if (o_blocks_count + add > n_blocks_count)
 947                 add = n_blocks_count - o_blocks_count;
 948
 949         if (o_blocks_count + add < n_blocks_count)
 950                 ext3_warning(sb, __FUNCTION__,
 951                              "will only finish group (%lu blocks, %u new)",
 952                              o_blocks_count + add, add);
 953
 954         /* See if the device is actually as big as what was requested */
 955         bh = sb_bread(sb, o_blocks_count + add -1);
 956         if (!bh) {
 957                 ext3_warning(sb, __FUNCTION__,
 958                              "can't read last block, resize aborted");
 959                 return -ENOSPC;
 960         }
 961         brelse(bh);
 962
 963         /* We will update the superblock, one block bitmap, and
 964          * one group descriptor via ext3_free_blocks().
 965          */
 966         handle = ext3_journal_start_sb(sb, 3);
 967         if (IS_ERR(handle)) {
 968                 err = PTR_ERR(handle);
 969                 ext3_warning(sb, __FUNCTION__, "error %d on journal start",err);
 970                 goto exit_put;
 971         }
 972
 973         lock_super(sb);
 974         if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
 975                 ext3_warning(sb, __FUNCTION__,
 976                              "multiple resizers run on filesystem!");
 977                 err = -EBUSY;
 978                 goto exit_put;
 979         }
 980
 981         if ((err = ext3_journal_get_write_access(handle,
 982                                                  EXT3_SB(sb)->s_sbh))) {
 983                 ext3_warning(sb, __FUNCTION__,
 984                              "error %d on journal write access", err);
 985                 unlock_super(sb);
 986                 ext3_journal_stop(handle);
 987                 goto exit_put;
 988         }
 989         es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
 990         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 991         sb->s_dirt = 1;
 992         unlock_super(sb);
 993         ext3_debug("freeing blocks %ld through %ld\n", o_blocks_count,
 994                    o_blocks_count + add);
 995         ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
 996         ext3_debug("freed blocks %ld through %ld\n", o_blocks_count,
 997                    o_blocks_count + add);
 998         if ((err = ext3_journal_stop(handle)))
 999                 goto exit_put;
1000         if (test_opt(sb, DEBUG))
1001                 printk(KERN_DEBUG "EXT3-fs: extended group to %u blocks\n",
1002                        le32_to_cpu(es->s_blocks_count));
1003         update_backups(sb, EXT3_SB(sb)->s_sbh->b_blocknr, (char *)es,
1004                        sizeof(struct ext3_super_block));
1005 exit_put:
1006         return err;
1007 } /* ext3_group_extend */