fs/ext4/resize.c

   1 /*
   2  *  linux/fs/ext4/resize.c
   3  *
   4  * Support for resizing an ext4 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 EXT4FS_DEBUG
  13
  14 #include <linux/smp_lock.h>
  15 #include <linux/ext4_jbd2.h>
  16
  17 #include <linux/errno.h>
  18 #include <linux/slab.h>
  19
  20
  21 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  22 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  23
  24 static int verify_group_input(struct super_block *sb,
  25                               struct ext4_new_group_data *input)
  26 {
  27         struct ext4_sb_info *sbi = EXT4_SB(sb);
  28         struct ext4_super_block *es = sbi->s_es;
  29         ext4_fsblk_t start = ext4_blocks_count(es);
  30         ext4_fsblk_t end = start + input->blocks_count;
  31         unsigned group = input->group;
  32         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  33         unsigned overhead = ext4_bg_has_super(sb, group) ?
  34                 (1 + ext4_bg_num_gdb(sb, group) +
  35                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  36         ext4_fsblk_t metaend = start + overhead;
  37         struct buffer_head *bh = NULL;
  38         ext4_grpblk_t free_blocks_count, offset;
  39         int err = -EINVAL;
  40
  41         input->free_blocks_count = free_blocks_count =
  42                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  43
  44         if (test_opt(sb, DEBUG))
  45                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
  46                        "(%d free, %u reserved)\n",
  47                        ext4_bg_has_super(sb, input->group) ? "normal" :
  48                        "no-super", input->group, input->blocks_count,
  49                        free_blocks_count, input->reserved_blocks);
  50
  51         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
  52         if (group != sbi->s_groups_count)
  53                 ext4_warning(sb, __FUNCTION__,
  54                              "Cannot add at group %u (only %lu groups)",
  55                              input->group, sbi->s_groups_count);
  56         else if (offset != 0)
  57                         ext4_warning(sb, __FUNCTION__, "Last group not full");
  58         else if (input->reserved_blocks > input->blocks_count / 5)
  59                 ext4_warning(sb, __FUNCTION__, "Reserved blocks too high (%u)",
  60                              input->reserved_blocks);
  61         else if (free_blocks_count < 0)
  62                 ext4_warning(sb, __FUNCTION__, "Bad blocks count %u",
  63                              input->blocks_count);
  64         else if (!(bh = sb_bread(sb, end - 1)))
  65                 ext4_warning(sb, __FUNCTION__,
  66                              "Cannot read last block (%llu)",
  67                              end - 1);
  68         else if (outside(input->block_bitmap, start, end))
  69                 ext4_warning(sb, __FUNCTION__,
  70                              "Block bitmap not in group (block %llu)",
  71                              (unsigned long long)input->block_bitmap);
  72         else if (outside(input->inode_bitmap, start, end))
  73                 ext4_warning(sb, __FUNCTION__,
  74                              "Inode bitmap not in group (block %llu)",
  75                              (unsigned long long)input->inode_bitmap);
  76         else if (outside(input->inode_table, start, end) ||
  77                  outside(itend - 1, start, end))
  78                 ext4_warning(sb, __FUNCTION__,
  79                              "Inode table not in group (blocks %llu-%llu)",
  80                              (unsigned long long)input->inode_table, itend - 1);
  81         else if (input->inode_bitmap == input->block_bitmap)
  82                 ext4_warning(sb, __FUNCTION__,
  83                              "Block bitmap same as inode bitmap (%llu)",
  84                              (unsigned long long)input->block_bitmap);
  85         else if (inside(input->block_bitmap, input->inode_table, itend))
  86                 ext4_warning(sb, __FUNCTION__,
  87                              "Block bitmap (%llu) in inode table (%llu-%llu)",
  88                              (unsigned long long)input->block_bitmap,
  89                              (unsigned long long)input->inode_table, itend - 1);
  90         else if (inside(input->inode_bitmap, input->inode_table, itend))
  91                 ext4_warning(sb, __FUNCTION__,
  92                              "Inode bitmap (%llu) in inode table (%llu-%llu)",
  93                              (unsigned long long)input->inode_bitmap,
  94                              (unsigned long long)input->inode_table, itend - 1);
  95         else if (inside(input->block_bitmap, start, metaend))
  96                 ext4_warning(sb, __FUNCTION__,
  97                              "Block bitmap (%llu) in GDT table"
  98                              " (%llu-%llu)",
  99                              (unsigned long long)input->block_bitmap,
 100                              start, metaend - 1);
 101         else if (inside(input->inode_bitmap, start, metaend))
 102                 ext4_warning(sb, __FUNCTION__,
 103                              "Inode bitmap (%llu) in GDT table"
 104                              " (%llu-%llu)",
 105                              (unsigned long long)input->inode_bitmap,
 106                              start, metaend - 1);
 107         else if (inside(input->inode_table, start, metaend) ||
 108                  inside(itend - 1, start, metaend))
 109                 ext4_warning(sb, __FUNCTION__,
 110                              "Inode table (%llu-%llu) overlaps"
 111                              "GDT table (%llu-%llu)",
 112                              (unsigned long long)input->inode_table,
 113                              itend - 1, start, metaend - 1);
 114         else
 115                 err = 0;
 116         brelse(bh);
 117
 118         return err;
 119 }
 120
 121 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 122                                   ext4_fsblk_t blk)
 123 {
 124         struct buffer_head *bh;
 125         int err;
 126
 127         bh = sb_getblk(sb, blk);
 128         if (!bh)
 129                 return ERR_PTR(-EIO);
 130         if ((err = ext4_journal_get_write_access(handle, bh))) {
 131                 brelse(bh);
 132                 bh = ERR_PTR(err);
 133         } else {
 134                 lock_buffer(bh);
 135                 memset(bh->b_data, 0, sb->s_blocksize);
 136                 set_buffer_uptodate(bh);
 137                 unlock_buffer(bh);
 138         }
 139
 140         return bh;
 141 }
 142
 143 /*
 144  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 145  * need to use it within a single byte (to ensure we get endianness right).
 146  * We can use memset for the rest of the bitmap as there are no other users.
 147  */
 148 static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 149 {
 150         int i;
 151
 152         if (start_bit >= end_bit)
 153                 return;
 154
 155         ext4_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 156         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 157                 ext4_set_bit(i, bitmap);
 158         if (i < end_bit)
 159                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 160 }
 161
 162 /*
 163  * Set up the block and inode bitmaps, and the inode table for the new group.
 164  * This doesn't need to be part of the main transaction, since we are only
 165  * changing blocks outside the actual filesystem.  We still do journaling to
 166  * ensure the recovery is correct in case of a failure just after resize.
 167  * If any part of this fails, we simply abort the resize.
 168  */
 169 static int setup_new_group_blocks(struct super_block *sb,
 170                                   struct ext4_new_group_data *input)
 171 {
 172         struct ext4_sb_info *sbi = EXT4_SB(sb);
 173         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
 174         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 175                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 176         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
 177         struct buffer_head *bh;
 178         handle_t *handle;
 179         ext4_fsblk_t block;
 180         ext4_grpblk_t bit;
 181         int i;
 182         int err = 0, err2;
 183
 184         handle = ext4_journal_start_sb(sb, reserved_gdb + gdblocks +
 185                                        2 + sbi->s_itb_per_group);
 186         if (IS_ERR(handle))
 187                 return PTR_ERR(handle);
 188
 189         lock_super(sb);
 190         if (input->group != sbi->s_groups_count) {
 191                 err = -EBUSY;
 192                 goto exit_journal;
 193         }
 194
 195         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 196                 err = PTR_ERR(bh);
 197                 goto exit_journal;
 198         }
 199
 200         if (ext4_bg_has_super(sb, input->group)) {
 201                 ext4_debug("mark backup superblock %#04lx (+0)\n", start);
 202                 ext4_set_bit(0, bh->b_data);
 203         }
 204
 205         /* Copy all of the GDT blocks into the backup in this group */
 206         for (i = 0, bit = 1, block = start + 1;
 207              i < gdblocks; i++, block++, bit++) {
 208                 struct buffer_head *gdb;
 209
 210                 ext4_debug("update backup group %#04lx (+%d)\n", block, bit);
 211
 212                 gdb = sb_getblk(sb, block);
 213                 if (!gdb) {
 214                         err = -EIO;
 215                         goto exit_bh;
 216                 }
 217                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
 218                         brelse(gdb);
 219                         goto exit_bh;
 220                 }
 221                 lock_buffer(bh);
 222                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, bh->b_size);
 223                 set_buffer_uptodate(gdb);
 224                 unlock_buffer(bh);
 225                 ext4_journal_dirty_metadata(handle, gdb);
 226                 ext4_set_bit(bit, bh->b_data);
 227                 brelse(gdb);
 228         }
 229
 230         /* Zero out all of the reserved backup group descriptor table blocks */
 231         for (i = 0, bit = gdblocks + 1, block = start + bit;
 232              i < reserved_gdb; i++, block++, bit++) {
 233                 struct buffer_head *gdb;
 234
 235                 ext4_debug("clear reserved block %#04lx (+%d)\n", block, bit);
 236
 237                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 238                         err = PTR_ERR(bh);
 239                         goto exit_bh;
 240                 }
 241                 ext4_journal_dirty_metadata(handle, gdb);
 242                 ext4_set_bit(bit, bh->b_data);
 243                 brelse(gdb);
 244         }
 245         ext4_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
 246                    input->block_bitmap - start);
 247         ext4_set_bit(input->block_bitmap - start, bh->b_data);
 248         ext4_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
 249                    input->inode_bitmap - start);
 250         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
 251
 252         /* Zero out all of the inode table blocks */
 253         for (i = 0, block = input->inode_table, bit = block - start;
 254              i < sbi->s_itb_per_group; i++, bit++, block++) {
 255                 struct buffer_head *it;
 256
 257                 ext4_debug("clear inode block %#04lx (+%d)\n", block, bit);
 258                 if (IS_ERR(it = bclean(handle, sb, block))) {
 259                         err = PTR_ERR(it);
 260                         goto exit_bh;
 261                 }
 262                 ext4_journal_dirty_metadata(handle, it);
 263                 brelse(it);
 264                 ext4_set_bit(bit, bh->b_data);
 265         }
 266         mark_bitmap_end(input->blocks_count, EXT4_BLOCKS_PER_GROUP(sb),
 267                         bh->b_data);
 268         ext4_journal_dirty_metadata(handle, bh);
 269         brelse(bh);
 270
 271         /* Mark unused entries in inode bitmap used */
 272         ext4_debug("clear inode bitmap %#04x (+%ld)\n",
 273                    input->inode_bitmap, input->inode_bitmap - start);
 274         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 275                 err = PTR_ERR(bh);
 276                 goto exit_journal;
 277         }
 278
 279         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), EXT4_BLOCKS_PER_GROUP(sb),
 280                         bh->b_data);
 281         ext4_journal_dirty_metadata(handle, bh);
 282 exit_bh:
 283         brelse(bh);
 284
 285 exit_journal:
 286         unlock_super(sb);
 287         if ((err2 = ext4_journal_stop(handle)) && !err)
 288                 err = err2;
 289
 290         return err;
 291 }
 292
 293
 294 /*
 295  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 296  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 297  * calling this for the first time.  In a sparse filesystem it will be the
 298  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 299  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 300  */
 301 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 302                                   unsigned *five, unsigned *seven)
 303 {
 304         unsigned *min = three;
 305         int mult = 3;
 306         unsigned ret;
 307
 308         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 309                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 310                 ret = *min;
 311                 *min += 1;
 312                 return ret;
 313         }
 314
 315         if (*five < *min) {
 316                 min = five;
 317                 mult = 5;
 318         }
 319         if (*seven < *min) {
 320                 min = seven;
 321                 mult = 7;
 322         }
 323
 324         ret = *min;
 325         *min *= mult;
 326
 327         return ret;
 328 }
 329
 330 /*
 331  * Check that all of the backup GDT blocks are held in the primary GDT block.
 332  * It is assumed that they are stored in group order.  Returns the number of
 333  * groups in current filesystem that have BACKUPS, or -ve error code.
 334  */
 335 static int verify_reserved_gdb(struct super_block *sb,
 336                                struct buffer_head *primary)
 337 {
 338         const ext4_fsblk_t blk = primary->b_blocknr;
 339         const unsigned long end = EXT4_SB(sb)->s_groups_count;
 340         unsigned three = 1;
 341         unsigned five = 5;
 342         unsigned seven = 7;
 343         unsigned grp;
 344         __le32 *p = (__le32 *)primary->b_data;
 345         int gdbackups = 0;
 346
 347         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 348                 if (le32_to_cpu(*p++) !=
 349                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 350                         ext4_warning(sb, __FUNCTION__,
 351                                      "reserved GDT %llu"
 352                                      " missing grp %d (%llu)",
 353                                      blk, grp,
 354                                      grp *
 355                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 356                                      blk);
 357                         return -EINVAL;
 358                 }
 359                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 360                         return -EFBIG;
 361         }
 362
 363         return gdbackups;
 364 }
 365
 366 /*
 367  * Called when we need to bring a reserved group descriptor table block into
 368  * use from the resize inode.  The primary copy of the new GDT block currently
 369  * is an indirect block (under the double indirect block in the resize inode).
 370  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 371  * block, in group order.  Even though we know all the block numbers we need,
 372  * we check to ensure that the resize inode has actually reserved these blocks.
 373  *
 374  * Don't need to update the block bitmaps because the blocks are still in use.
 375  *
 376  * We get all of the error cases out of the way, so that we are sure to not
 377  * fail once we start modifying the data on disk, because JBD has no rollback.
 378  */
 379 static int add_new_gdb(handle_t *handle, struct inode *inode,
 380                        struct ext4_new_group_data *input,
 381                        struct buffer_head **primary)
 382 {
 383         struct super_block *sb = inode->i_sb;
 384         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 385         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 386         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 387         struct buffer_head **o_group_desc, **n_group_desc;
 388         struct buffer_head *dind;
 389         int gdbackups;
 390         struct ext4_iloc iloc;
 391         __le32 *data;
 392         int err;
 393
 394         if (test_opt(sb, DEBUG))
 395                 printk(KERN_DEBUG
 396                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 397                        gdb_num);
 398
 399         /*
 400          * If we are not using the primary superblock/GDT copy don't resize,
 401          * because the user tools have no way of handling this.  Probably a
 402          * bad time to do it anyways.
 403          */
 404         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 405             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 406                 ext4_warning(sb, __FUNCTION__,
 407                         "won't resize using backup superblock at %llu",
 408                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 409                 return -EPERM;
 410         }
 411
 412         *primary = sb_bread(sb, gdblock);
 413         if (!*primary)
 414                 return -EIO;
 415
 416         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 417                 err = gdbackups;
 418                 goto exit_bh;
 419         }
 420
 421         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 422         dind = sb_bread(sb, le32_to_cpu(*data));
 423         if (!dind) {
 424                 err = -EIO;
 425                 goto exit_bh;
 426         }
 427
 428         data = (__le32 *)dind->b_data;
 429         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 430                 ext4_warning(sb, __FUNCTION__,
 431                              "new group %u GDT block %llu not reserved",
 432                              input->group, gdblock);
 433                 err = -EINVAL;
 434                 goto exit_dind;
 435         }
 436
 437         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
 438                 goto exit_dind;
 439
 440         if ((err = ext4_journal_get_write_access(handle, *primary)))
 441                 goto exit_sbh;
 442
 443         if ((err = ext4_journal_get_write_access(handle, dind)))
 444                 goto exit_primary;
 445
 446         /* ext4_reserve_inode_write() gets a reference on the iloc */
 447         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 448                 goto exit_dindj;
 449
 450         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 451                         GFP_KERNEL);
 452         if (!n_group_desc) {
 453                 err = -ENOMEM;
 454                 ext4_warning (sb, __FUNCTION__,
 455                               "not enough memory for %lu groups", gdb_num + 1);
 456                 goto exit_inode;
 457         }
 458
 459         /*
 460          * Finally, we have all of the possible failures behind us...
 461          *
 462          * Remove new GDT block from inode double-indirect block and clear out
 463          * the new GDT block for use (which also "frees" the backup GDT blocks
 464          * from the reserved inode).  We don't need to change the bitmaps for
 465          * these blocks, because they are marked as in-use from being in the
 466          * reserved inode, and will become GDT blocks (primary and backup).
 467          */
 468         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 469         ext4_journal_dirty_metadata(handle, dind);
 470         brelse(dind);
 471         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 472         ext4_mark_iloc_dirty(handle, inode, &iloc);
 473         memset((*primary)->b_data, 0, sb->s_blocksize);
 474         ext4_journal_dirty_metadata(handle, *primary);
 475
 476         o_group_desc = EXT4_SB(sb)->s_group_desc;
 477         memcpy(n_group_desc, o_group_desc,
 478                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 479         n_group_desc[gdb_num] = *primary;
 480         EXT4_SB(sb)->s_group_desc = n_group_desc;
 481         EXT4_SB(sb)->s_gdb_count++;
 482         kfree(o_group_desc);
 483
 484         es->s_reserved_gdt_blocks =
 485                 cpu_to_le16(le16_to_cpu(es->s_reserved_gdt_blocks) - 1);
 486         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 487
 488         return 0;
 489
 490 exit_inode:
 491         //ext4_journal_release_buffer(handle, iloc.bh);
 492         brelse(iloc.bh);
 493 exit_dindj:
 494         //ext4_journal_release_buffer(handle, dind);
 495 exit_primary:
 496         //ext4_journal_release_buffer(handle, *primary);
 497 exit_sbh:
 498         //ext4_journal_release_buffer(handle, *primary);
 499 exit_dind:
 500         brelse(dind);
 501 exit_bh:
 502         brelse(*primary);
 503
 504         ext4_debug("leaving with error %d\n", err);
 505         return err;
 506 }
 507
 508 /*
 509  * Called when we are adding a new group which has a backup copy of each of
 510  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 511  * We need to add these reserved backup GDT blocks to the resize inode, so
 512  * that they are kept for future resizing and not allocated to files.
 513  *
 514  * Each reserved backup GDT block will go into a different indirect block.
 515  * The indirect blocks are actually the primary reserved GDT blocks,
 516  * so we know in advance what their block numbers are.  We only get the
 517  * double-indirect block to verify it is pointing to the primary reserved
 518  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 519  * backup GDT blocks are stored in their reserved primary GDT block.
 520  */
 521 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 522                               struct ext4_new_group_data *input)
 523 {
 524         struct super_block *sb = inode->i_sb;
 525         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 526         struct buffer_head **primary;
 527         struct buffer_head *dind;
 528         struct ext4_iloc iloc;
 529         ext4_fsblk_t blk;
 530         __le32 *data, *end;
 531         int gdbackups = 0;
 532         int res, i;
 533         int err;
 534
 535         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_KERNEL);
 536         if (!primary)
 537                 return -ENOMEM;
 538
 539         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 540         dind = sb_bread(sb, le32_to_cpu(*data));
 541         if (!dind) {
 542                 err = -EIO;
 543                 goto exit_free;
 544         }
 545
 546         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 547         data = (__le32 *)dind->b_data + EXT4_SB(sb)->s_gdb_count;
 548         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 549
 550         /* Get each reserved primary GDT block and verify it holds backups */
 551         for (res = 0; res < reserved_gdb; res++, blk++) {
 552                 if (le32_to_cpu(*data) != blk) {
 553                         ext4_warning(sb, __FUNCTION__,
 554                                      "reserved block %llu"
 555                                      " not at offset %ld",
 556                                      blk,
 557                                      (long)(data - (__le32 *)dind->b_data));
 558                         err = -EINVAL;
 559                         goto exit_bh;
 560                 }
 561                 primary[res] = sb_bread(sb, blk);
 562                 if (!primary[res]) {
 563                         err = -EIO;
 564                         goto exit_bh;
 565                 }
 566                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 567                         brelse(primary[res]);
 568                         err = gdbackups;
 569                         goto exit_bh;
 570                 }
 571                 if (++data >= end)
 572                         data = (__le32 *)dind->b_data;
 573         }
 574
 575         for (i = 0; i < reserved_gdb; i++) {
 576                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 577                         /*
 578                         int j;
 579                         for (j = 0; j < i; j++)
 580                                 ext4_journal_release_buffer(handle, primary[j]);
 581                          */
 582                         goto exit_bh;
 583                 }
 584         }
 585
 586         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 587                 goto exit_bh;
 588
 589         /*
 590          * Finally we can add each of the reserved backup GDT blocks from
 591          * the new group to its reserved primary GDT block.
 592          */
 593         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
 594         for (i = 0; i < reserved_gdb; i++) {
 595                 int err2;
 596                 data = (__le32 *)primary[i]->b_data;
 597                 /* printk("reserving backup %lu[%u] = %lu\n",
 598                        primary[i]->b_blocknr, gdbackups,
 599                        blk + primary[i]->b_blocknr); */
 600                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 601                 err2 = ext4_journal_dirty_metadata(handle, primary[i]);
 602                 if (!err)
 603                         err = err2;
 604         }
 605         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 606         ext4_mark_iloc_dirty(handle, inode, &iloc);
 607
 608 exit_bh:
 609         while (--res >= 0)
 610                 brelse(primary[res]);
 611         brelse(dind);
 612
 613 exit_free:
 614         kfree(primary);
 615
 616         return err;
 617 }
 618
 619 /*
 620  * Update the backup copies of the ext4 metadata.  These don't need to be part
 621  * of the main resize transaction, because e2fsck will re-write them if there
 622  * is a problem (basically only OOM will cause a problem).  However, we
 623  * _should_ update the backups if possible, in case the primary gets trashed
 624  * for some reason and we need to run e2fsck from a backup superblock.  The
 625  * important part is that the new block and inode counts are in the backup
 626  * superblocks, and the location of the new group metadata in the GDT backups.
 627  *
 628  * We do not need lock_super() for this, because these blocks are not
 629  * otherwise touched by the filesystem code when it is mounted.  We don't
 630  * need to worry about last changing from sbi->s_groups_count, because the
 631  * worst that can happen is that we do not copy the full number of backups
 632  * at this time.  The resize which changed s_groups_count will backup again.
 633  */
 634 static void update_backups(struct super_block *sb,
 635                            int blk_off, char *data, int size)
 636 {
 637         struct ext4_sb_info *sbi = EXT4_SB(sb);
 638         const unsigned long last = sbi->s_groups_count;
 639         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 640         unsigned three = 1;
 641         unsigned five = 5;
 642         unsigned seven = 7;
 643         unsigned group;
 644         int rest = sb->s_blocksize - size;
 645         handle_t *handle;
 646         int err = 0, err2;
 647
 648         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 649         if (IS_ERR(handle)) {
 650                 group = 1;
 651                 err = PTR_ERR(handle);
 652                 goto exit_err;
 653         }
 654
 655         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 656                 struct buffer_head *bh;
 657
 658                 /* Out of journal space, and can't get more - abort - so sad */
 659                 if (handle->h_buffer_credits == 0 &&
 660                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 661                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 662                         break;
 663
 664                 bh = sb_getblk(sb, group * bpg + blk_off);
 665                 if (!bh) {
 666                         err = -EIO;
 667                         break;
 668                 }
 669                 ext4_debug("update metadata backup %#04lx\n",
 670                           (unsigned long)bh->b_blocknr);
 671                 if ((err = ext4_journal_get_write_access(handle, bh)))
 672                         break;
 673                 lock_buffer(bh);
 674                 memcpy(bh->b_data, data, size);
 675                 if (rest)
 676                         memset(bh->b_data + size, 0, rest);
 677                 set_buffer_uptodate(bh);
 678                 unlock_buffer(bh);
 679                 ext4_journal_dirty_metadata(handle, bh);
 680                 brelse(bh);
 681         }
 682         if ((err2 = ext4_journal_stop(handle)) && !err)
 683                 err = err2;
 684
 685         /*
 686          * Ugh! Need to have e2fsck write the backup copies.  It is too
 687          * late to revert the resize, we shouldn't fail just because of
 688          * the backup copies (they are only needed in case of corruption).
 689          *
 690          * However, if we got here we have a journal problem too, so we
 691          * can't really start a transaction to mark the superblock.
 692          * Chicken out and just set the flag on the hope it will be written
 693          * to disk, and if not - we will simply wait until next fsck.
 694          */
 695 exit_err:
 696         if (err) {
 697                 ext4_warning(sb, __FUNCTION__,
 698                              "can't update backup for group %d (err %d), "
 699                              "forcing fsck on next reboot", group, err);
 700                 sbi->s_mount_state &= ~EXT4_VALID_FS;
 701                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
 702                 mark_buffer_dirty(sbi->s_sbh);
 703         }
 704 }
 705
 706 /* Add group descriptor data to an existing or new group descriptor block.
 707  * Ensure we handle all possible error conditions _before_ we start modifying
 708  * the filesystem, because we cannot abort the transaction and not have it
 709  * write the data to disk.
 710  *
 711  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 712  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 713  *
 714  * We only need to hold the superblock lock while we are actually adding
 715  * in the new group's counts to the superblock.  Prior to that we have
 716  * not really "added" the group at all.  We re-check that we are still
 717  * adding in the last group in case things have changed since verifying.
 718  */
 719 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 720 {
 721         struct ext4_sb_info *sbi = EXT4_SB(sb);
 722         struct ext4_super_block *es = sbi->s_es;
 723         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 724                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 725         struct buffer_head *primary = NULL;
 726         struct ext4_group_desc *gdp;
 727         struct inode *inode = NULL;
 728         handle_t *handle;
 729         int gdb_off, gdb_num;
 730         int err, err2;
 731
 732         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 733         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
 734
 735         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
 736                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 737                 ext4_warning(sb, __FUNCTION__,
 738                              "Can't resize non-sparse filesystem further");
 739                 return -EPERM;
 740         }
 741
 742         if (ext4_blocks_count(es) + input->blocks_count <
 743             ext4_blocks_count(es)) {
 744                 ext4_warning(sb, __FUNCTION__, "blocks_count overflow\n");
 745                 return -EINVAL;
 746         }
 747
 748         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
 749             le32_to_cpu(es->s_inodes_count)) {
 750                 ext4_warning(sb, __FUNCTION__, "inodes_count overflow\n");
 751                 return -EINVAL;
 752         }
 753
 754         if (reserved_gdb || gdb_off == 0) {
 755                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
 756                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)){
 757                         ext4_warning(sb, __FUNCTION__,
 758                                      "No reserved GDT blocks, can't resize");
 759                         return -EPERM;
 760                 }
 761                 inode = iget(sb, EXT4_RESIZE_INO);
 762                 if (!inode || is_bad_inode(inode)) {
 763                         ext4_warning(sb, __FUNCTION__,
 764                                      "Error opening resize inode");
 765                         iput(inode);
 766                         return -ENOENT;
 767                 }
 768         }
 769
 770         if ((err = verify_group_input(sb, input)))
 771                 goto exit_put;
 772
 773         if ((err = setup_new_group_blocks(sb, input)))
 774                 goto exit_put;
 775
 776         /*
 777          * We will always be modifying at least the superblock and a GDT
 778          * block.  If we are adding a group past the last current GDT block,
 779          * we will also modify the inode and the dindirect block.  If we
 780          * are adding a group with superblock/GDT backups  we will also
 781          * modify each of the reserved GDT dindirect blocks.
 782          */
 783         handle = ext4_journal_start_sb(sb,
 784                                        ext4_bg_has_super(sb, input->group) ?
 785                                        3 + reserved_gdb : 4);
 786         if (IS_ERR(handle)) {
 787                 err = PTR_ERR(handle);
 788                 goto exit_put;
 789         }
 790
 791         lock_super(sb);
 792         if (input->group != sbi->s_groups_count) {
 793                 ext4_warning(sb, __FUNCTION__,
 794                              "multiple resizers run on filesystem!");
 795                 err = -EBUSY;
 796                 goto exit_journal;
 797         }
 798
 799         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
 800                 goto exit_journal;
 801
 802         /*
 803          * We will only either add reserved group blocks to a backup group
 804          * or remove reserved blocks for the first group in a new group block.
 805          * Doing both would be mean more complex code, and sane people don't
 806          * use non-sparse filesystems anymore.  This is already checked above.
 807          */
 808         if (gdb_off) {
 809                 primary = sbi->s_group_desc[gdb_num];
 810                 if ((err = ext4_journal_get_write_access(handle, primary)))
 811                         goto exit_journal;
 812
 813                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
 814                     (err = reserve_backup_gdb(handle, inode, input)))
 815                         goto exit_journal;
 816         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 817                 goto exit_journal;
 818
 819         /*
 820          * OK, now we've set up the new group.  Time to make it active.
 821          *
 822          * Current kernels don't lock all allocations via lock_super(),
 823          * so we have to be safe wrt. concurrent accesses the group
 824          * data.  So we need to be careful to set all of the relevant
 825          * group descriptor data etc. *before* we enable the group.
 826          *
 827          * The key field here is sbi->s_groups_count: as long as
 828          * that retains its old value, nobody is going to access the new
 829          * group.
 830          *
 831          * So first we update all the descriptor metadata for the new
 832          * group; then we update the total disk blocks count; then we
 833          * update the groups count to enable the group; then finally we
 834          * update the free space counts so that the system can start
 835          * using the new disk blocks.
 836          */
 837
 838         /* Update group descriptor block for new group */
 839         gdp = (struct ext4_group_desc *)primary->b_data + gdb_off;
 840
 841         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
 842         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
 843         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
 844         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 845         gdp->bg_free_inodes_count = cpu_to_le16(EXT4_INODES_PER_GROUP(sb));
 846
 847         /*
 848          * Make the new blocks and inodes valid next.  We do this before
 849          * increasing the group count so that once the group is enabled,
 850          * all of its blocks and inodes are already valid.
 851          *
 852          * We always allocate group-by-group, then block-by-block or
 853          * inode-by-inode within a group, so enabling these
 854          * blocks/inodes before the group is live won't actually let us
 855          * allocate the new space yet.
 856          */
 857         ext4_blocks_count_set(es, ext4_blocks_count(es) +
 858                 input->blocks_count);
 859         es->s_inodes_count = cpu_to_le32(le32_to_cpu(es->s_inodes_count) +
 860                 EXT4_INODES_PER_GROUP(sb));
 861
 862         /*
 863          * We need to protect s_groups_count against other CPUs seeing
 864          * inconsistent state in the superblock.
 865          *
 866          * The precise rules we use are:
 867          *
 868          * * Writers of s_groups_count *must* hold lock_super
 869          * AND
 870          * * Writers must perform a smp_wmb() after updating all dependent
 871          *   data and before modifying the groups count
 872          *
 873          * * Readers must hold lock_super() over the access
 874          * OR
 875          * * Readers must perform an smp_rmb() after reading the groups count
 876          *   and before reading any dependent data.
 877          *
 878          * NB. These rules can be relaxed when checking the group count
 879          * while freeing data, as we can only allocate from a block
 880          * group after serialising against the group count, and we can
 881          * only then free after serialising in turn against that
 882          * allocation.
 883          */
 884         smp_wmb();
 885
 886         /* Update the global fs size fields */
 887         sbi->s_groups_count++;
 888
 889         ext4_journal_dirty_metadata(handle, primary);
 890
 891         /* Update the reserved block counts only once the new group is
 892          * active. */
 893         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 894                 input->reserved_blocks);
 895
 896         /* Update the free space counts */
 897         percpu_counter_mod(&sbi->s_freeblocks_counter,
 898                            input->free_blocks_count);
 899         percpu_counter_mod(&sbi->s_freeinodes_counter,
 900                            EXT4_INODES_PER_GROUP(sb));
 901
 902         ext4_journal_dirty_metadata(handle, sbi->s_sbh);
 903         sb->s_dirt = 1;
 904
 905 exit_journal:
 906         unlock_super(sb);
 907         if ((err2 = ext4_journal_stop(handle)) && !err)
 908                 err = err2;
 909         if (!err) {
 910                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 911                                sizeof(struct ext4_super_block));
 912                 update_backups(sb, primary->b_blocknr, primary->b_data,
 913                                primary->b_size);
 914         }
 915 exit_put:
 916         iput(inode);
 917         return err;
 918 } /* ext4_group_add */
 919
 920 /* Extend the filesystem to the new number of blocks specified.  This entry
 921  * point is only used to extend the current filesystem to the end of the last
 922  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 923  * for emergencies (because it has no dependencies on reserved blocks).
 924  *
 925  * If we _really_ wanted, we could use default values to call ext4_group_add()
 926  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 927  * GDT blocks are reserved to grow to the desired size.
 928  */
 929 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 930                       ext4_fsblk_t n_blocks_count)
 931 {
 932         ext4_fsblk_t o_blocks_count;
 933         unsigned long o_groups_count;
 934         ext4_grpblk_t last;
 935         ext4_grpblk_t add;
 936         struct buffer_head * bh;
 937         handle_t *handle;
 938         int err;
 939         unsigned long freed_blocks;
 940
 941         /* We don't need to worry about locking wrt other resizers just
 942          * yet: we're going to revalidate es->s_blocks_count after
 943          * taking lock_super() below. */
 944         o_blocks_count = ext4_blocks_count(es);
 945         o_groups_count = EXT4_SB(sb)->s_groups_count;
 946
 947         if (test_opt(sb, DEBUG))
 948                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
 949                        o_blocks_count, n_blocks_count);
 950
 951         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 952                 return 0;
 953
 954         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
 955                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
 956                         " too large to resize to %llu blocks safely\n",
 957                         sb->s_id, n_blocks_count);
 958                 if (sizeof(sector_t) < 8)
 959                         ext4_warning(sb, __FUNCTION__,
 960                         "CONFIG_LBD not enabled\n");
 961                 return -EINVAL;
 962         }
 963
 964         if (n_blocks_count < o_blocks_count) {
 965                 ext4_warning(sb, __FUNCTION__,
 966                              "can't shrink FS - resize aborted");
 967                 return -EBUSY;
 968         }
 969
 970         /* Handle the remaining blocks in the last group only. */
 971         ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
 972
 973         if (last == 0) {
 974                 ext4_warning(sb, __FUNCTION__,
 975                              "need to use ext2online to resize further");
 976                 return -EPERM;
 977         }
 978
 979         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
 980
 981         if (o_blocks_count + add < o_blocks_count) {
 982                 ext4_warning(sb, __FUNCTION__, "blocks_count overflow");
 983                 return -EINVAL;
 984         }
 985
 986         if (o_blocks_count + add > n_blocks_count)
 987                 add = n_blocks_count - o_blocks_count;
 988
 989         if (o_blocks_count + add < n_blocks_count)
 990                 ext4_warning(sb, __FUNCTION__,
 991                              "will only finish group (%llu"
 992                              " blocks, %u new)",
 993                              o_blocks_count + add, add);
 994
 995         /* See if the device is actually as big as what was requested */
 996         bh = sb_bread(sb, o_blocks_count + add -1);
 997         if (!bh) {
 998                 ext4_warning(sb, __FUNCTION__,
 999                              "can't read last block, resize aborted");
1000                 return -ENOSPC;
1001         }
1002         brelse(bh);
1003
1004         /* We will update the superblock, one block bitmap, and
1005          * one group descriptor via ext4_free_blocks().
1006          */
1007         handle = ext4_journal_start_sb(sb, 3);
1008         if (IS_ERR(handle)) {
1009                 err = PTR_ERR(handle);
1010                 ext4_warning(sb, __FUNCTION__, "error %d on journal start",err);
1011                 goto exit_put;
1012         }
1013
1014         lock_super(sb);
1015         if (o_blocks_count != ext4_blocks_count(es)) {
1016                 ext4_warning(sb, __FUNCTION__,
1017                              "multiple resizers run on filesystem!");
1018                 unlock_super(sb);
1019                 err = -EBUSY;
1020                 goto exit_put;
1021         }
1022
1023         if ((err = ext4_journal_get_write_access(handle,
1024                                                  EXT4_SB(sb)->s_sbh))) {
1025                 ext4_warning(sb, __FUNCTION__,
1026                              "error %d on journal write access", err);
1027                 unlock_super(sb);
1028                 ext4_journal_stop(handle);
1029                 goto exit_put;
1030         }
1031         ext4_blocks_count_set(es, o_blocks_count + add);
1032         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
1033         sb->s_dirt = 1;
1034         unlock_super(sb);
1035         ext4_debug("freeing blocks %lu through %llu\n", o_blocks_count,
1036                    o_blocks_count + add);
1037         ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1038         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1039                    o_blocks_count + add);
1040         if ((err = ext4_journal_stop(handle)))
1041                 goto exit_put;
1042         if (test_opt(sb, DEBUG))
1043                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1044                        ext4_blocks_count(es));
1045         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1046                        sizeof(struct ext4_super_block));
1047 exit_put:
1048         return err;
1049 } /* ext4_group_extend */