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/ext4_jbd2.h>
  15
  16 #include <linux/errno.h>
  17 #include <linux/slab.h>
  18
  19 #include "group.h"
  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         ext4_group_t 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  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 145  * If that fails, restart the transaction & regain write access for the
 146  * buffer head which is used for block_bitmap modifications.
 147  */
 148 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 149                                          struct buffer_head *bh)
 150 {
 151         int err;
 152
 153         if (handle->h_buffer_credits >= thresh)
 154                 return 0;
 155
 156         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 157         if (err < 0)
 158                 return err;
 159         if (err) {
 160                 if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 161                         return err;
 162                 if ((err = ext4_journal_get_write_access(handle, bh)))
 163                         return err;
 164         }
 165
 166         return 0;
 167 }
 168
 169 /*
 170  * Set up the block and inode bitmaps, and the inode table for the new group.
 171  * This doesn't need to be part of the main transaction, since we are only
 172  * changing blocks outside the actual filesystem.  We still do journaling to
 173  * ensure the recovery is correct in case of a failure just after resize.
 174  * If any part of this fails, we simply abort the resize.
 175  */
 176 static int setup_new_group_blocks(struct super_block *sb,
 177                                   struct ext4_new_group_data *input)
 178 {
 179         struct ext4_sb_info *sbi = EXT4_SB(sb);
 180         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
 181         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 182                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 183         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
 184         struct buffer_head *bh;
 185         handle_t *handle;
 186         ext4_fsblk_t block;
 187         ext4_grpblk_t bit;
 188         int i;
 189         int err = 0, err2;
 190
 191         /* This transaction may be extended/restarted along the way */
 192         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 193
 194         if (IS_ERR(handle))
 195                 return PTR_ERR(handle);
 196
 197         lock_super(sb);
 198         if (input->group != sbi->s_groups_count) {
 199                 err = -EBUSY;
 200                 goto exit_journal;
 201         }
 202
 203         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 204                 err = PTR_ERR(bh);
 205                 goto exit_journal;
 206         }
 207
 208         if (ext4_bg_has_super(sb, input->group)) {
 209                 ext4_debug("mark backup superblock %#04llx (+0)\n", start);
 210                 ext4_set_bit(0, bh->b_data);
 211         }
 212
 213         /* Copy all of the GDT blocks into the backup in this group */
 214         for (i = 0, bit = 1, block = start + 1;
 215              i < gdblocks; i++, block++, bit++) {
 216                 struct buffer_head *gdb;
 217
 218                 ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
 219
 220                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 221                         goto exit_bh;
 222
 223                 gdb = sb_getblk(sb, block);
 224                 if (!gdb) {
 225                         err = -EIO;
 226                         goto exit_bh;
 227                 }
 228                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
 229                         brelse(gdb);
 230                         goto exit_bh;
 231                 }
 232                 lock_buffer(gdb);
 233                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
 234                 set_buffer_uptodate(gdb);
 235                 unlock_buffer(gdb);
 236                 ext4_journal_dirty_metadata(handle, gdb);
 237                 ext4_set_bit(bit, bh->b_data);
 238                 brelse(gdb);
 239         }
 240
 241         /* Zero out all of the reserved backup group descriptor table blocks */
 242         for (i = 0, bit = gdblocks + 1, block = start + bit;
 243              i < reserved_gdb; i++, block++, bit++) {
 244                 struct buffer_head *gdb;
 245
 246                 ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
 247
 248                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 249                         goto exit_bh;
 250
 251                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 252                         err = PTR_ERR(bh);
 253                         goto exit_bh;
 254                 }
 255                 ext4_journal_dirty_metadata(handle, gdb);
 256                 ext4_set_bit(bit, bh->b_data);
 257                 brelse(gdb);
 258         }
 259         ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
 260                    input->block_bitmap - start);
 261         ext4_set_bit(input->block_bitmap - start, bh->b_data);
 262         ext4_debug("mark inode bitmap %#04llx (+%llu)\n", input->inode_bitmap,
 263                    input->inode_bitmap - start);
 264         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
 265
 266         /* Zero out all of the inode table blocks */
 267         for (i = 0, block = input->inode_table, bit = block - start;
 268              i < sbi->s_itb_per_group; i++, bit++, block++) {
 269                 struct buffer_head *it;
 270
 271                 ext4_debug("clear inode block %#04llx (+%d)\n", block, bit);
 272
 273                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 274                         goto exit_bh;
 275
 276                 if (IS_ERR(it = bclean(handle, sb, block))) {
 277                         err = PTR_ERR(it);
 278                         goto exit_bh;
 279                 }
 280                 ext4_journal_dirty_metadata(handle, it);
 281                 brelse(it);
 282                 ext4_set_bit(bit, bh->b_data);
 283         }
 284
 285         if ((err = extend_or_restart_transaction(handle, 2, bh)))
 286                 goto exit_bh;
 287
 288         mark_bitmap_end(input->blocks_count, EXT4_BLOCKS_PER_GROUP(sb),
 289                         bh->b_data);
 290         ext4_journal_dirty_metadata(handle, bh);
 291         brelse(bh);
 292
 293         /* Mark unused entries in inode bitmap used */
 294         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
 295                    input->inode_bitmap, input->inode_bitmap - start);
 296         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 297                 err = PTR_ERR(bh);
 298                 goto exit_journal;
 299         }
 300
 301         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), EXT4_BLOCKS_PER_GROUP(sb),
 302                         bh->b_data);
 303         ext4_journal_dirty_metadata(handle, bh);
 304 exit_bh:
 305         brelse(bh);
 306
 307 exit_journal:
 308         unlock_super(sb);
 309         if ((err2 = ext4_journal_stop(handle)) && !err)
 310                 err = err2;
 311
 312         return err;
 313 }
 314
 315 /*
 316  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 317  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 318  * calling this for the first time.  In a sparse filesystem it will be the
 319  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 320  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 321  */
 322 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 323                                   unsigned *five, unsigned *seven)
 324 {
 325         unsigned *min = three;
 326         int mult = 3;
 327         unsigned ret;
 328
 329         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 330                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 331                 ret = *min;
 332                 *min += 1;
 333                 return ret;
 334         }
 335
 336         if (*five < *min) {
 337                 min = five;
 338                 mult = 5;
 339         }
 340         if (*seven < *min) {
 341                 min = seven;
 342                 mult = 7;
 343         }
 344
 345         ret = *min;
 346         *min *= mult;
 347
 348         return ret;
 349 }
 350
 351 /*
 352  * Check that all of the backup GDT blocks are held in the primary GDT block.
 353  * It is assumed that they are stored in group order.  Returns the number of
 354  * groups in current filesystem that have BACKUPS, or -ve error code.
 355  */
 356 static int verify_reserved_gdb(struct super_block *sb,
 357                                struct buffer_head *primary)
 358 {
 359         const ext4_fsblk_t blk = primary->b_blocknr;
 360         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
 361         unsigned three = 1;
 362         unsigned five = 5;
 363         unsigned seven = 7;
 364         unsigned grp;
 365         __le32 *p = (__le32 *)primary->b_data;
 366         int gdbackups = 0;
 367
 368         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 369                 if (le32_to_cpu(*p++) !=
 370                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 371                         ext4_warning(sb, __FUNCTION__,
 372                                      "reserved GDT %llu"
 373                                      " missing grp %d (%llu)",
 374                                      blk, grp,
 375                                      grp *
 376                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 377                                      blk);
 378                         return -EINVAL;
 379                 }
 380                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 381                         return -EFBIG;
 382         }
 383
 384         return gdbackups;
 385 }
 386
 387 /*
 388  * Called when we need to bring a reserved group descriptor table block into
 389  * use from the resize inode.  The primary copy of the new GDT block currently
 390  * is an indirect block (under the double indirect block in the resize inode).
 391  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 392  * block, in group order.  Even though we know all the block numbers we need,
 393  * we check to ensure that the resize inode has actually reserved these blocks.
 394  *
 395  * Don't need to update the block bitmaps because the blocks are still in use.
 396  *
 397  * We get all of the error cases out of the way, so that we are sure to not
 398  * fail once we start modifying the data on disk, because JBD has no rollback.
 399  */
 400 static int add_new_gdb(handle_t *handle, struct inode *inode,
 401                        struct ext4_new_group_data *input,
 402                        struct buffer_head **primary)
 403 {
 404         struct super_block *sb = inode->i_sb;
 405         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 406         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 407         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 408         struct buffer_head **o_group_desc, **n_group_desc;
 409         struct buffer_head *dind;
 410         int gdbackups;
 411         struct ext4_iloc iloc;
 412         __le32 *data;
 413         int err;
 414
 415         if (test_opt(sb, DEBUG))
 416                 printk(KERN_DEBUG
 417                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 418                        gdb_num);
 419
 420         /*
 421          * If we are not using the primary superblock/GDT copy don't resize,
 422          * because the user tools have no way of handling this.  Probably a
 423          * bad time to do it anyways.
 424          */
 425         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 426             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 427                 ext4_warning(sb, __FUNCTION__,
 428                         "won't resize using backup superblock at %llu",
 429                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 430                 return -EPERM;
 431         }
 432
 433         *primary = sb_bread(sb, gdblock);
 434         if (!*primary)
 435                 return -EIO;
 436
 437         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 438                 err = gdbackups;
 439                 goto exit_bh;
 440         }
 441
 442         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 443         dind = sb_bread(sb, le32_to_cpu(*data));
 444         if (!dind) {
 445                 err = -EIO;
 446                 goto exit_bh;
 447         }
 448
 449         data = (__le32 *)dind->b_data;
 450         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 451                 ext4_warning(sb, __FUNCTION__,
 452                              "new group %u GDT block %llu not reserved",
 453                              input->group, gdblock);
 454                 err = -EINVAL;
 455                 goto exit_dind;
 456         }
 457
 458         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
 459                 goto exit_dind;
 460
 461         if ((err = ext4_journal_get_write_access(handle, *primary)))
 462                 goto exit_sbh;
 463
 464         if ((err = ext4_journal_get_write_access(handle, dind)))
 465                 goto exit_primary;
 466
 467         /* ext4_reserve_inode_write() gets a reference on the iloc */
 468         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 469                 goto exit_dindj;
 470
 471         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 472                         GFP_KERNEL);
 473         if (!n_group_desc) {
 474                 err = -ENOMEM;
 475                 ext4_warning (sb, __FUNCTION__,
 476                               "not enough memory for %lu groups", gdb_num + 1);
 477                 goto exit_inode;
 478         }
 479
 480         /*
 481          * Finally, we have all of the possible failures behind us...
 482          *
 483          * Remove new GDT block from inode double-indirect block and clear out
 484          * the new GDT block for use (which also "frees" the backup GDT blocks
 485          * from the reserved inode).  We don't need to change the bitmaps for
 486          * these blocks, because they are marked as in-use from being in the
 487          * reserved inode, and will become GDT blocks (primary and backup).
 488          */
 489         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 490         ext4_journal_dirty_metadata(handle, dind);
 491         brelse(dind);
 492         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 493         ext4_mark_iloc_dirty(handle, inode, &iloc);
 494         memset((*primary)->b_data, 0, sb->s_blocksize);
 495         ext4_journal_dirty_metadata(handle, *primary);
 496
 497         o_group_desc = EXT4_SB(sb)->s_group_desc;
 498         memcpy(n_group_desc, o_group_desc,
 499                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 500         n_group_desc[gdb_num] = *primary;
 501         EXT4_SB(sb)->s_group_desc = n_group_desc;
 502         EXT4_SB(sb)->s_gdb_count++;
 503         kfree(o_group_desc);
 504
 505         es->s_reserved_gdt_blocks =
 506                 cpu_to_le16(le16_to_cpu(es->s_reserved_gdt_blocks) - 1);
 507         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 508
 509         return 0;
 510
 511 exit_inode:
 512         //ext4_journal_release_buffer(handle, iloc.bh);
 513         brelse(iloc.bh);
 514 exit_dindj:
 515         //ext4_journal_release_buffer(handle, dind);
 516 exit_primary:
 517         //ext4_journal_release_buffer(handle, *primary);
 518 exit_sbh:
 519         //ext4_journal_release_buffer(handle, *primary);
 520 exit_dind:
 521         brelse(dind);
 522 exit_bh:
 523         brelse(*primary);
 524
 525         ext4_debug("leaving with error %d\n", err);
 526         return err;
 527 }
 528
 529 /*
 530  * Called when we are adding a new group which has a backup copy of each of
 531  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 532  * We need to add these reserved backup GDT blocks to the resize inode, so
 533  * that they are kept for future resizing and not allocated to files.
 534  *
 535  * Each reserved backup GDT block will go into a different indirect block.
 536  * The indirect blocks are actually the primary reserved GDT blocks,
 537  * so we know in advance what their block numbers are.  We only get the
 538  * double-indirect block to verify it is pointing to the primary reserved
 539  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 540  * backup GDT blocks are stored in their reserved primary GDT block.
 541  */
 542 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 543                               struct ext4_new_group_data *input)
 544 {
 545         struct super_block *sb = inode->i_sb;
 546         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 547         struct buffer_head **primary;
 548         struct buffer_head *dind;
 549         struct ext4_iloc iloc;
 550         ext4_fsblk_t blk;
 551         __le32 *data, *end;
 552         int gdbackups = 0;
 553         int res, i;
 554         int err;
 555
 556         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_KERNEL);
 557         if (!primary)
 558                 return -ENOMEM;
 559
 560         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 561         dind = sb_bread(sb, le32_to_cpu(*data));
 562         if (!dind) {
 563                 err = -EIO;
 564                 goto exit_free;
 565         }
 566
 567         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 568         data = (__le32 *)dind->b_data + EXT4_SB(sb)->s_gdb_count;
 569         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 570
 571         /* Get each reserved primary GDT block and verify it holds backups */
 572         for (res = 0; res < reserved_gdb; res++, blk++) {
 573                 if (le32_to_cpu(*data) != blk) {
 574                         ext4_warning(sb, __FUNCTION__,
 575                                      "reserved block %llu"
 576                                      " not at offset %ld",
 577                                      blk,
 578                                      (long)(data - (__le32 *)dind->b_data));
 579                         err = -EINVAL;
 580                         goto exit_bh;
 581                 }
 582                 primary[res] = sb_bread(sb, blk);
 583                 if (!primary[res]) {
 584                         err = -EIO;
 585                         goto exit_bh;
 586                 }
 587                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 588                         brelse(primary[res]);
 589                         err = gdbackups;
 590                         goto exit_bh;
 591                 }
 592                 if (++data >= end)
 593                         data = (__le32 *)dind->b_data;
 594         }
 595
 596         for (i = 0; i < reserved_gdb; i++) {
 597                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 598                         /*
 599                         int j;
 600                         for (j = 0; j < i; j++)
 601                                 ext4_journal_release_buffer(handle, primary[j]);
 602                          */
 603                         goto exit_bh;
 604                 }
 605         }
 606
 607         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 608                 goto exit_bh;
 609
 610         /*
 611          * Finally we can add each of the reserved backup GDT blocks from
 612          * the new group to its reserved primary GDT block.
 613          */
 614         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
 615         for (i = 0; i < reserved_gdb; i++) {
 616                 int err2;
 617                 data = (__le32 *)primary[i]->b_data;
 618                 /* printk("reserving backup %lu[%u] = %lu\n",
 619                        primary[i]->b_blocknr, gdbackups,
 620                        blk + primary[i]->b_blocknr); */
 621                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 622                 err2 = ext4_journal_dirty_metadata(handle, primary[i]);
 623                 if (!err)
 624                         err = err2;
 625         }
 626         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 627         ext4_mark_iloc_dirty(handle, inode, &iloc);
 628
 629 exit_bh:
 630         while (--res >= 0)
 631                 brelse(primary[res]);
 632         brelse(dind);
 633
 634 exit_free:
 635         kfree(primary);
 636
 637         return err;
 638 }
 639
 640 /*
 641  * Update the backup copies of the ext4 metadata.  These don't need to be part
 642  * of the main resize transaction, because e2fsck will re-write them if there
 643  * is a problem (basically only OOM will cause a problem).  However, we
 644  * _should_ update the backups if possible, in case the primary gets trashed
 645  * for some reason and we need to run e2fsck from a backup superblock.  The
 646  * important part is that the new block and inode counts are in the backup
 647  * superblocks, and the location of the new group metadata in the GDT backups.
 648  *
 649  * We do not need lock_super() for this, because these blocks are not
 650  * otherwise touched by the filesystem code when it is mounted.  We don't
 651  * need to worry about last changing from sbi->s_groups_count, because the
 652  * worst that can happen is that we do not copy the full number of backups
 653  * at this time.  The resize which changed s_groups_count will backup again.
 654  */
 655 static void update_backups(struct super_block *sb,
 656                            int blk_off, char *data, int size)
 657 {
 658         struct ext4_sb_info *sbi = EXT4_SB(sb);
 659         const ext4_group_t last = sbi->s_groups_count;
 660         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 661         unsigned three = 1;
 662         unsigned five = 5;
 663         unsigned seven = 7;
 664         ext4_group_t group;
 665         int rest = sb->s_blocksize - size;
 666         handle_t *handle;
 667         int err = 0, err2;
 668
 669         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 670         if (IS_ERR(handle)) {
 671                 group = 1;
 672                 err = PTR_ERR(handle);
 673                 goto exit_err;
 674         }
 675
 676         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 677                 struct buffer_head *bh;
 678
 679                 /* Out of journal space, and can't get more - abort - so sad */
 680                 if (handle->h_buffer_credits == 0 &&
 681                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 682                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 683                         break;
 684
 685                 bh = sb_getblk(sb, group * bpg + blk_off);
 686                 if (!bh) {
 687                         err = -EIO;
 688                         break;
 689                 }
 690                 ext4_debug("update metadata backup %#04lx\n",
 691                           (unsigned long)bh->b_blocknr);
 692                 if ((err = ext4_journal_get_write_access(handle, bh)))
 693                         break;
 694                 lock_buffer(bh);
 695                 memcpy(bh->b_data, data, size);
 696                 if (rest)
 697                         memset(bh->b_data + size, 0, rest);
 698                 set_buffer_uptodate(bh);
 699                 unlock_buffer(bh);
 700                 ext4_journal_dirty_metadata(handle, bh);
 701                 brelse(bh);
 702         }
 703         if ((err2 = ext4_journal_stop(handle)) && !err)
 704                 err = err2;
 705
 706         /*
 707          * Ugh! Need to have e2fsck write the backup copies.  It is too
 708          * late to revert the resize, we shouldn't fail just because of
 709          * the backup copies (they are only needed in case of corruption).
 710          *
 711          * However, if we got here we have a journal problem too, so we
 712          * can't really start a transaction to mark the superblock.
 713          * Chicken out and just set the flag on the hope it will be written
 714          * to disk, and if not - we will simply wait until next fsck.
 715          */
 716 exit_err:
 717         if (err) {
 718                 ext4_warning(sb, __FUNCTION__,
 719                              "can't update backup for group %lu (err %d), "
 720                              "forcing fsck on next reboot", group, err);
 721                 sbi->s_mount_state &= ~EXT4_VALID_FS;
 722                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
 723                 mark_buffer_dirty(sbi->s_sbh);
 724         }
 725 }
 726
 727 /* Add group descriptor data to an existing or new group descriptor block.
 728  * Ensure we handle all possible error conditions _before_ we start modifying
 729  * the filesystem, because we cannot abort the transaction and not have it
 730  * write the data to disk.
 731  *
 732  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 733  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 734  *
 735  * We only need to hold the superblock lock while we are actually adding
 736  * in the new group's counts to the superblock.  Prior to that we have
 737  * not really "added" the group at all.  We re-check that we are still
 738  * adding in the last group in case things have changed since verifying.
 739  */
 740 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 741 {
 742         struct ext4_sb_info *sbi = EXT4_SB(sb);
 743         struct ext4_super_block *es = sbi->s_es;
 744         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 745                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 746         struct buffer_head *primary = NULL;
 747         struct ext4_group_desc *gdp;
 748         struct inode *inode = NULL;
 749         handle_t *handle;
 750         int gdb_off, gdb_num;
 751         int err, err2;
 752
 753         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 754         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
 755
 756         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
 757                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 758                 ext4_warning(sb, __FUNCTION__,
 759                              "Can't resize non-sparse filesystem further");
 760                 return -EPERM;
 761         }
 762
 763         if (ext4_blocks_count(es) + input->blocks_count <
 764             ext4_blocks_count(es)) {
 765                 ext4_warning(sb, __FUNCTION__, "blocks_count overflow\n");
 766                 return -EINVAL;
 767         }
 768
 769         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
 770             le32_to_cpu(es->s_inodes_count)) {
 771                 ext4_warning(sb, __FUNCTION__, "inodes_count overflow\n");
 772                 return -EINVAL;
 773         }
 774
 775         if (reserved_gdb || gdb_off == 0) {
 776                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
 777                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)){
 778                         ext4_warning(sb, __FUNCTION__,
 779                                      "No reserved GDT blocks, can't resize");
 780                         return -EPERM;
 781                 }
 782                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
 783                 if (IS_ERR(inode)) {
 784                         ext4_warning(sb, __FUNCTION__,
 785                                      "Error opening resize inode");
 786                         return PTR_ERR(inode);
 787                 }
 788         }
 789
 790         if ((err = verify_group_input(sb, input)))
 791                 goto exit_put;
 792
 793         if ((err = setup_new_group_blocks(sb, input)))
 794                 goto exit_put;
 795
 796         /*
 797          * We will always be modifying at least the superblock and a GDT
 798          * block.  If we are adding a group past the last current GDT block,
 799          * we will also modify the inode and the dindirect block.  If we
 800          * are adding a group with superblock/GDT backups  we will also
 801          * modify each of the reserved GDT dindirect blocks.
 802          */
 803         handle = ext4_journal_start_sb(sb,
 804                                        ext4_bg_has_super(sb, input->group) ?
 805                                        3 + reserved_gdb : 4);
 806         if (IS_ERR(handle)) {
 807                 err = PTR_ERR(handle);
 808                 goto exit_put;
 809         }
 810
 811         lock_super(sb);
 812         if (input->group != sbi->s_groups_count) {
 813                 ext4_warning(sb, __FUNCTION__,
 814                              "multiple resizers run on filesystem!");
 815                 err = -EBUSY;
 816                 goto exit_journal;
 817         }
 818
 819         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
 820                 goto exit_journal;
 821
 822         /*
 823          * We will only either add reserved group blocks to a backup group
 824          * or remove reserved blocks for the first group in a new group block.
 825          * Doing both would be mean more complex code, and sane people don't
 826          * use non-sparse filesystems anymore.  This is already checked above.
 827          */
 828         if (gdb_off) {
 829                 primary = sbi->s_group_desc[gdb_num];
 830                 if ((err = ext4_journal_get_write_access(handle, primary)))
 831                         goto exit_journal;
 832
 833                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
 834                     (err = reserve_backup_gdb(handle, inode, input)))
 835                         goto exit_journal;
 836         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 837                 goto exit_journal;
 838
 839         /*
 840          * OK, now we've set up the new group.  Time to make it active.
 841          *
 842          * Current kernels don't lock all allocations via lock_super(),
 843          * so we have to be safe wrt. concurrent accesses the group
 844          * data.  So we need to be careful to set all of the relevant
 845          * group descriptor data etc. *before* we enable the group.
 846          *
 847          * The key field here is sbi->s_groups_count: as long as
 848          * that retains its old value, nobody is going to access the new
 849          * group.
 850          *
 851          * So first we update all the descriptor metadata for the new
 852          * group; then we update the total disk blocks count; then we
 853          * update the groups count to enable the group; then finally we
 854          * update the free space counts so that the system can start
 855          * using the new disk blocks.
 856          */
 857
 858         /* Update group descriptor block for new group */
 859         gdp = (struct ext4_group_desc *)primary->b_data + gdb_off;
 860
 861         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
 862         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
 863         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
 864         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 865         gdp->bg_free_inodes_count = cpu_to_le16(EXT4_INODES_PER_GROUP(sb));
 866         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
 867
 868         /*
 869          * Make the new blocks and inodes valid next.  We do this before
 870          * increasing the group count so that once the group is enabled,
 871          * all of its blocks and inodes are already valid.
 872          *
 873          * We always allocate group-by-group, then block-by-block or
 874          * inode-by-inode within a group, so enabling these
 875          * blocks/inodes before the group is live won't actually let us
 876          * allocate the new space yet.
 877          */
 878         ext4_blocks_count_set(es, ext4_blocks_count(es) +
 879                 input->blocks_count);
 880         es->s_inodes_count = cpu_to_le32(le32_to_cpu(es->s_inodes_count) +
 881                 EXT4_INODES_PER_GROUP(sb));
 882
 883         /*
 884          * We need to protect s_groups_count against other CPUs seeing
 885          * inconsistent state in the superblock.
 886          *
 887          * The precise rules we use are:
 888          *
 889          * * Writers of s_groups_count *must* hold lock_super
 890          * AND
 891          * * Writers must perform a smp_wmb() after updating all dependent
 892          *   data and before modifying the groups count
 893          *
 894          * * Readers must hold lock_super() over the access
 895          * OR
 896          * * Readers must perform an smp_rmb() after reading the groups count
 897          *   and before reading any dependent data.
 898          *
 899          * NB. These rules can be relaxed when checking the group count
 900          * while freeing data, as we can only allocate from a block
 901          * group after serialising against the group count, and we can
 902          * only then free after serialising in turn against that
 903          * allocation.
 904          */
 905         smp_wmb();
 906
 907         /* Update the global fs size fields */
 908         sbi->s_groups_count++;
 909
 910         ext4_journal_dirty_metadata(handle, primary);
 911
 912         /* Update the reserved block counts only once the new group is
 913          * active. */
 914         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 915                 input->reserved_blocks);
 916
 917         /* Update the free space counts */
 918         percpu_counter_add(&sbi->s_freeblocks_counter,
 919                            input->free_blocks_count);
 920         percpu_counter_add(&sbi->s_freeinodes_counter,
 921                            EXT4_INODES_PER_GROUP(sb));
 922
 923         ext4_journal_dirty_metadata(handle, sbi->s_sbh);
 924         sb->s_dirt = 1;
 925
 926 exit_journal:
 927         unlock_super(sb);
 928         if ((err2 = ext4_journal_stop(handle)) && !err)
 929                 err = err2;
 930         if (!err) {
 931                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 932                                sizeof(struct ext4_super_block));
 933                 update_backups(sb, primary->b_blocknr, primary->b_data,
 934                                primary->b_size);
 935         }
 936 exit_put:
 937         iput(inode);
 938         return err;
 939 } /* ext4_group_add */
 940
 941 /* Extend the filesystem to the new number of blocks specified.  This entry
 942  * point is only used to extend the current filesystem to the end of the last
 943  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 944  * for emergencies (because it has no dependencies on reserved blocks).
 945  *
 946  * If we _really_ wanted, we could use default values to call ext4_group_add()
 947  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 948  * GDT blocks are reserved to grow to the desired size.
 949  */
 950 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 951                       ext4_fsblk_t n_blocks_count)
 952 {
 953         ext4_fsblk_t o_blocks_count;
 954         ext4_group_t o_groups_count;
 955         ext4_grpblk_t last;
 956         ext4_grpblk_t add;
 957         struct buffer_head * bh;
 958         handle_t *handle;
 959         int err;
 960         unsigned long freed_blocks;
 961
 962         /* We don't need to worry about locking wrt other resizers just
 963          * yet: we're going to revalidate es->s_blocks_count after
 964          * taking lock_super() below. */
 965         o_blocks_count = ext4_blocks_count(es);
 966         o_groups_count = EXT4_SB(sb)->s_groups_count;
 967
 968         if (test_opt(sb, DEBUG))
 969                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
 970                        o_blocks_count, n_blocks_count);
 971
 972         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 973                 return 0;
 974
 975         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
 976                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
 977                         " too large to resize to %llu blocks safely\n",
 978                         sb->s_id, n_blocks_count);
 979                 if (sizeof(sector_t) < 8)
 980                         ext4_warning(sb, __FUNCTION__,
 981                         "CONFIG_LBD not enabled\n");
 982                 return -EINVAL;
 983         }
 984
 985         if (n_blocks_count < o_blocks_count) {
 986                 ext4_warning(sb, __FUNCTION__,
 987                              "can't shrink FS - resize aborted");
 988                 return -EBUSY;
 989         }
 990
 991         /* Handle the remaining blocks in the last group only. */
 992         ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
 993
 994         if (last == 0) {
 995                 ext4_warning(sb, __FUNCTION__,
 996                              "need to use ext2online to resize further");
 997                 return -EPERM;
 998         }
 999
1000         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1001
1002         if (o_blocks_count + add < o_blocks_count) {
1003                 ext4_warning(sb, __FUNCTION__, "blocks_count overflow");
1004                 return -EINVAL;
1005         }
1006
1007         if (o_blocks_count + add > n_blocks_count)
1008                 add = n_blocks_count - o_blocks_count;
1009
1010         if (o_blocks_count + add < n_blocks_count)
1011                 ext4_warning(sb, __FUNCTION__,
1012                              "will only finish group (%llu"
1013                              " blocks, %u new)",
1014                              o_blocks_count + add, add);
1015
1016         /* See if the device is actually as big as what was requested */
1017         bh = sb_bread(sb, o_blocks_count + add -1);
1018         if (!bh) {
1019                 ext4_warning(sb, __FUNCTION__,
1020                              "can't read last block, resize aborted");
1021                 return -ENOSPC;
1022         }
1023         brelse(bh);
1024
1025         /* We will update the superblock, one block bitmap, and
1026          * one group descriptor via ext4_free_blocks().
1027          */
1028         handle = ext4_journal_start_sb(sb, 3);
1029         if (IS_ERR(handle)) {
1030                 err = PTR_ERR(handle);
1031                 ext4_warning(sb, __FUNCTION__, "error %d on journal start",err);
1032                 goto exit_put;
1033         }
1034
1035         lock_super(sb);
1036         if (o_blocks_count != ext4_blocks_count(es)) {
1037                 ext4_warning(sb, __FUNCTION__,
1038                              "multiple resizers run on filesystem!");
1039                 unlock_super(sb);
1040                 ext4_journal_stop(handle);
1041                 err = -EBUSY;
1042                 goto exit_put;
1043         }
1044
1045         if ((err = ext4_journal_get_write_access(handle,
1046                                                  EXT4_SB(sb)->s_sbh))) {
1047                 ext4_warning(sb, __FUNCTION__,
1048                              "error %d on journal write access", err);
1049                 unlock_super(sb);
1050                 ext4_journal_stop(handle);
1051                 goto exit_put;
1052         }
1053         ext4_blocks_count_set(es, o_blocks_count + add);
1054         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
1055         sb->s_dirt = 1;
1056         unlock_super(sb);
1057         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1058                    o_blocks_count + add);
1059         ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1060         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1061                    o_blocks_count + add);
1062         if ((err = ext4_journal_stop(handle)))
1063                 goto exit_put;
1064         if (test_opt(sb, DEBUG))
1065                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1066                        ext4_blocks_count(es));
1067         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1068                        sizeof(struct ext4_super_block));
1069 exit_put:
1070         return err;
1071 } /* ext4_group_extend */