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/errno.h>
  15 #include <linux/slab.h>
  16
  17 #include "ext4_jbd2.h"
  18 #include "group.h"
  19
  20 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  21 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  22
  23 static int verify_group_input(struct super_block *sb,
  24                               struct ext4_new_group_data *input)
  25 {
  26         struct ext4_sb_info *sbi = EXT4_SB(sb);
  27         struct ext4_super_block *es = sbi->s_es;
  28         ext4_fsblk_t start = ext4_blocks_count(es);
  29         ext4_fsblk_t end = start + input->blocks_count;
  30         ext4_group_t group = input->group;
  31         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  32         unsigned overhead = ext4_bg_has_super(sb, group) ?
  33                 (1 + ext4_bg_num_gdb(sb, group) +
  34                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  35         ext4_fsblk_t metaend = start + overhead;
  36         struct buffer_head *bh = NULL;
  37         ext4_grpblk_t free_blocks_count, offset;
  38         int err = -EINVAL;
  39
  40         input->free_blocks_count = free_blocks_count =
  41                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  42
  43         if (test_opt(sb, DEBUG))
  44                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
  45                        "(%d free, %u reserved)\n",
  46                        ext4_bg_has_super(sb, input->group) ? "normal" :
  47                        "no-super", input->group, input->blocks_count,
  48                        free_blocks_count, input->reserved_blocks);
  49
  50         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
  51         if (group != sbi->s_groups_count)
  52                 ext4_warning(sb, __func__,
  53                              "Cannot add at group %u (only %u groups)",
  54                              input->group, sbi->s_groups_count);
  55         else if (offset != 0)
  56                         ext4_warning(sb, __func__, "Last group not full");
  57         else if (input->reserved_blocks > input->blocks_count / 5)
  58                 ext4_warning(sb, __func__, "Reserved blocks too high (%u)",
  59                              input->reserved_blocks);
  60         else if (free_blocks_count < 0)
  61                 ext4_warning(sb, __func__, "Bad blocks count %u",
  62                              input->blocks_count);
  63         else if (!(bh = sb_bread(sb, end - 1)))
  64                 ext4_warning(sb, __func__,
  65                              "Cannot read last block (%llu)",
  66                              end - 1);
  67         else if (outside(input->block_bitmap, start, end))
  68                 ext4_warning(sb, __func__,
  69                              "Block bitmap not in group (block %llu)",
  70                              (unsigned long long)input->block_bitmap);
  71         else if (outside(input->inode_bitmap, start, end))
  72                 ext4_warning(sb, __func__,
  73                              "Inode bitmap not in group (block %llu)",
  74                              (unsigned long long)input->inode_bitmap);
  75         else if (outside(input->inode_table, start, end) ||
  76                  outside(itend - 1, start, end))
  77                 ext4_warning(sb, __func__,
  78                              "Inode table not in group (blocks %llu-%llu)",
  79                              (unsigned long long)input->inode_table, itend - 1);
  80         else if (input->inode_bitmap == input->block_bitmap)
  81                 ext4_warning(sb, __func__,
  82                              "Block bitmap same as inode bitmap (%llu)",
  83                              (unsigned long long)input->block_bitmap);
  84         else if (inside(input->block_bitmap, input->inode_table, itend))
  85                 ext4_warning(sb, __func__,
  86                              "Block bitmap (%llu) in inode table (%llu-%llu)",
  87                              (unsigned long long)input->block_bitmap,
  88                              (unsigned long long)input->inode_table, itend - 1);
  89         else if (inside(input->inode_bitmap, input->inode_table, itend))
  90                 ext4_warning(sb, __func__,
  91                              "Inode bitmap (%llu) in inode table (%llu-%llu)",
  92                              (unsigned long long)input->inode_bitmap,
  93                              (unsigned long long)input->inode_table, itend - 1);
  94         else if (inside(input->block_bitmap, start, metaend))
  95                 ext4_warning(sb, __func__,
  96                              "Block bitmap (%llu) in GDT table"
  97                              " (%llu-%llu)",
  98                              (unsigned long long)input->block_bitmap,
  99                              start, metaend - 1);
 100         else if (inside(input->inode_bitmap, start, metaend))
 101                 ext4_warning(sb, __func__,
 102                              "Inode bitmap (%llu) in GDT table"
 103                              " (%llu-%llu)",
 104                              (unsigned long long)input->inode_bitmap,
 105                              start, metaend - 1);
 106         else if (inside(input->inode_table, start, metaend) ||
 107                  inside(itend - 1, start, metaend))
 108                 ext4_warning(sb, __func__,
 109                              "Inode table (%llu-%llu) overlaps"
 110                              "GDT table (%llu-%llu)",
 111                              (unsigned long long)input->inode_table,
 112                              itend - 1, start, metaend - 1);
 113         else
 114                 err = 0;
 115         brelse(bh);
 116
 117         return err;
 118 }
 119
 120 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 121                                   ext4_fsblk_t blk)
 122 {
 123         struct buffer_head *bh;
 124         int err;
 125
 126         bh = sb_getblk(sb, blk);
 127         if (!bh)
 128                 return ERR_PTR(-EIO);
 129         if ((err = ext4_journal_get_write_access(handle, bh))) {
 130                 brelse(bh);
 131                 bh = ERR_PTR(err);
 132         } else {
 133                 lock_buffer(bh);
 134                 memset(bh->b_data, 0, sb->s_blocksize);
 135                 set_buffer_uptodate(bh);
 136                 unlock_buffer(bh);
 137         }
 138
 139         return bh;
 140 }
 141
 142 /*
 143  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 144  * If that fails, restart the transaction & regain write access for the
 145  * buffer head which is used for block_bitmap modifications.
 146  */
 147 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 148                                          struct buffer_head *bh)
 149 {
 150         int err;
 151
 152         if (ext4_handle_has_enough_credits(handle, thresh))
 153                 return 0;
 154
 155         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 156         if (err < 0)
 157                 return err;
 158         if (err) {
 159                 if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 160                         return err;
 161                 if ((err = ext4_journal_get_write_access(handle, bh)))
 162                         return err;
 163         }
 164
 165         return 0;
 166 }
 167
 168 /*
 169  * Set up the block and inode bitmaps, and the inode table for the new group.
 170  * This doesn't need to be part of the main transaction, since we are only
 171  * changing blocks outside the actual filesystem.  We still do journaling to
 172  * ensure the recovery is correct in case of a failure just after resize.
 173  * If any part of this fails, we simply abort the resize.
 174  */
 175 static int setup_new_group_blocks(struct super_block *sb,
 176                                   struct ext4_new_group_data *input)
 177 {
 178         struct ext4_sb_info *sbi = EXT4_SB(sb);
 179         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
 180         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 181                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 182         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
 183         struct buffer_head *bh;
 184         handle_t *handle;
 185         ext4_fsblk_t block;
 186         ext4_grpblk_t bit;
 187         int i;
 188         int err = 0, err2;
 189
 190         /* This transaction may be extended/restarted along the way */
 191         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 192
 193         if (IS_ERR(handle))
 194                 return PTR_ERR(handle);
 195
 196         lock_super(sb);
 197         if (input->group != sbi->s_groups_count) {
 198                 err = -EBUSY;
 199                 goto exit_journal;
 200         }
 201
 202         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 203                 err = PTR_ERR(bh);
 204                 goto exit_journal;
 205         }
 206
 207         if (ext4_bg_has_super(sb, input->group)) {
 208                 ext4_debug("mark backup superblock %#04llx (+0)\n", start);
 209                 ext4_set_bit(0, bh->b_data);
 210         }
 211
 212         /* Copy all of the GDT blocks into the backup in this group */
 213         for (i = 0, bit = 1, block = start + 1;
 214              i < gdblocks; i++, block++, bit++) {
 215                 struct buffer_head *gdb;
 216
 217                 ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
 218
 219                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 220                         goto exit_bh;
 221
 222                 gdb = sb_getblk(sb, block);
 223                 if (!gdb) {
 224                         err = -EIO;
 225                         goto exit_bh;
 226                 }
 227                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
 228                         brelse(gdb);
 229                         goto exit_bh;
 230                 }
 231                 lock_buffer(gdb);
 232                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
 233                 set_buffer_uptodate(gdb);
 234                 unlock_buffer(gdb);
 235                 ext4_handle_dirty_metadata(handle, NULL, gdb);
 236                 ext4_set_bit(bit, bh->b_data);
 237                 brelse(gdb);
 238         }
 239
 240         /* Zero out all of the reserved backup group descriptor table blocks */
 241         for (i = 0, bit = gdblocks + 1, block = start + bit;
 242              i < reserved_gdb; i++, block++, bit++) {
 243                 struct buffer_head *gdb;
 244
 245                 ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
 246
 247                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 248                         goto exit_bh;
 249
 250                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 251                         err = PTR_ERR(bh);
 252                         goto exit_bh;
 253                 }
 254                 ext4_handle_dirty_metadata(handle, NULL, gdb);
 255                 ext4_set_bit(bit, bh->b_data);
 256                 brelse(gdb);
 257         }
 258         ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
 259                    input->block_bitmap - start);
 260         ext4_set_bit(input->block_bitmap - start, bh->b_data);
 261         ext4_debug("mark inode bitmap %#04llx (+%llu)\n", input->inode_bitmap,
 262                    input->inode_bitmap - start);
 263         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
 264
 265         /* Zero out all of the inode table blocks */
 266         for (i = 0, block = input->inode_table, bit = block - start;
 267              i < sbi->s_itb_per_group; i++, bit++, block++) {
 268                 struct buffer_head *it;
 269
 270                 ext4_debug("clear inode block %#04llx (+%d)\n", block, bit);
 271
 272                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 273                         goto exit_bh;
 274
 275                 if (IS_ERR(it = bclean(handle, sb, block))) {
 276                         err = PTR_ERR(it);
 277                         goto exit_bh;
 278                 }
 279                 ext4_handle_dirty_metadata(handle, NULL, it);
 280                 brelse(it);
 281                 ext4_set_bit(bit, bh->b_data);
 282         }
 283
 284         if ((err = extend_or_restart_transaction(handle, 2, bh)))
 285                 goto exit_bh;
 286
 287         mark_bitmap_end(input->blocks_count, sb->s_blocksize * 8, bh->b_data);
 288         ext4_handle_dirty_metadata(handle, NULL, bh);
 289         brelse(bh);
 290         /* Mark unused entries in inode bitmap used */
 291         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
 292                    input->inode_bitmap, input->inode_bitmap - start);
 293         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 294                 err = PTR_ERR(bh);
 295                 goto exit_journal;
 296         }
 297
 298         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
 299                         bh->b_data);
 300         ext4_handle_dirty_metadata(handle, NULL, bh);
 301 exit_bh:
 302         brelse(bh);
 303
 304 exit_journal:
 305         unlock_super(sb);
 306         if ((err2 = ext4_journal_stop(handle)) && !err)
 307                 err = err2;
 308
 309         return err;
 310 }
 311
 312 /*
 313  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 314  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 315  * calling this for the first time.  In a sparse filesystem it will be the
 316  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 317  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 318  */
 319 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 320                                   unsigned *five, unsigned *seven)
 321 {
 322         unsigned *min = three;
 323         int mult = 3;
 324         unsigned ret;
 325
 326         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 327                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 328                 ret = *min;
 329                 *min += 1;
 330                 return ret;
 331         }
 332
 333         if (*five < *min) {
 334                 min = five;
 335                 mult = 5;
 336         }
 337         if (*seven < *min) {
 338                 min = seven;
 339                 mult = 7;
 340         }
 341
 342         ret = *min;
 343         *min *= mult;
 344
 345         return ret;
 346 }
 347
 348 /*
 349  * Check that all of the backup GDT blocks are held in the primary GDT block.
 350  * It is assumed that they are stored in group order.  Returns the number of
 351  * groups in current filesystem that have BACKUPS, or -ve error code.
 352  */
 353 static int verify_reserved_gdb(struct super_block *sb,
 354                                struct buffer_head *primary)
 355 {
 356         const ext4_fsblk_t blk = primary->b_blocknr;
 357         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
 358         unsigned three = 1;
 359         unsigned five = 5;
 360         unsigned seven = 7;
 361         unsigned grp;
 362         __le32 *p = (__le32 *)primary->b_data;
 363         int gdbackups = 0;
 364
 365         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 366                 if (le32_to_cpu(*p++) !=
 367                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 368                         ext4_warning(sb, __func__,
 369                                      "reserved GDT %llu"
 370                                      " missing grp %d (%llu)",
 371                                      blk, grp,
 372                                      grp *
 373                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 374                                      blk);
 375                         return -EINVAL;
 376                 }
 377                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 378                         return -EFBIG;
 379         }
 380
 381         return gdbackups;
 382 }
 383
 384 /*
 385  * Called when we need to bring a reserved group descriptor table block into
 386  * use from the resize inode.  The primary copy of the new GDT block currently
 387  * is an indirect block (under the double indirect block in the resize inode).
 388  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 389  * block, in group order.  Even though we know all the block numbers we need,
 390  * we check to ensure that the resize inode has actually reserved these blocks.
 391  *
 392  * Don't need to update the block bitmaps because the blocks are still in use.
 393  *
 394  * We get all of the error cases out of the way, so that we are sure to not
 395  * fail once we start modifying the data on disk, because JBD has no rollback.
 396  */
 397 static int add_new_gdb(handle_t *handle, struct inode *inode,
 398                        struct ext4_new_group_data *input,
 399                        struct buffer_head **primary)
 400 {
 401         struct super_block *sb = inode->i_sb;
 402         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 403         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 404         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 405         struct buffer_head **o_group_desc, **n_group_desc;
 406         struct buffer_head *dind;
 407         int gdbackups;
 408         struct ext4_iloc iloc;
 409         __le32 *data;
 410         int err;
 411
 412         if (test_opt(sb, DEBUG))
 413                 printk(KERN_DEBUG
 414                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 415                        gdb_num);
 416
 417         /*
 418          * If we are not using the primary superblock/GDT copy don't resize,
 419          * because the user tools have no way of handling this.  Probably a
 420          * bad time to do it anyways.
 421          */
 422         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 423             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 424                 ext4_warning(sb, __func__,
 425                         "won't resize using backup superblock at %llu",
 426                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 427                 return -EPERM;
 428         }
 429
 430         *primary = sb_bread(sb, gdblock);
 431         if (!*primary)
 432                 return -EIO;
 433
 434         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 435                 err = gdbackups;
 436                 goto exit_bh;
 437         }
 438
 439         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 440         dind = sb_bread(sb, le32_to_cpu(*data));
 441         if (!dind) {
 442                 err = -EIO;
 443                 goto exit_bh;
 444         }
 445
 446         data = (__le32 *)dind->b_data;
 447         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 448                 ext4_warning(sb, __func__,
 449                              "new group %u GDT block %llu not reserved",
 450                              input->group, gdblock);
 451                 err = -EINVAL;
 452                 goto exit_dind;
 453         }
 454
 455         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
 456                 goto exit_dind;
 457
 458         if ((err = ext4_journal_get_write_access(handle, *primary)))
 459                 goto exit_sbh;
 460
 461         if ((err = ext4_journal_get_write_access(handle, dind)))
 462                 goto exit_primary;
 463
 464         /* ext4_reserve_inode_write() gets a reference on the iloc */
 465         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 466                 goto exit_dindj;
 467
 468         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 469                         GFP_NOFS);
 470         if (!n_group_desc) {
 471                 err = -ENOMEM;
 472                 ext4_warning(sb, __func__,
 473                               "not enough memory for %lu groups", gdb_num + 1);
 474                 goto exit_inode;
 475         }
 476
 477         /*
 478          * Finally, we have all of the possible failures behind us...
 479          *
 480          * Remove new GDT block from inode double-indirect block and clear out
 481          * the new GDT block for use (which also "frees" the backup GDT blocks
 482          * from the reserved inode).  We don't need to change the bitmaps for
 483          * these blocks, because they are marked as in-use from being in the
 484          * reserved inode, and will become GDT blocks (primary and backup).
 485          */
 486         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 487         ext4_handle_dirty_metadata(handle, NULL, dind);
 488         brelse(dind);
 489         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 490         ext4_mark_iloc_dirty(handle, inode, &iloc);
 491         memset((*primary)->b_data, 0, sb->s_blocksize);
 492         ext4_handle_dirty_metadata(handle, NULL, *primary);
 493
 494         o_group_desc = EXT4_SB(sb)->s_group_desc;
 495         memcpy(n_group_desc, o_group_desc,
 496                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 497         n_group_desc[gdb_num] = *primary;
 498         EXT4_SB(sb)->s_group_desc = n_group_desc;
 499         EXT4_SB(sb)->s_gdb_count++;
 500         kfree(o_group_desc);
 501
 502         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 503         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 504
 505         return 0;
 506
 507 exit_inode:
 508         /* ext4_journal_release_buffer(handle, iloc.bh); */
 509         brelse(iloc.bh);
 510 exit_dindj:
 511         /* ext4_journal_release_buffer(handle, dind); */
 512 exit_primary:
 513         /* ext4_journal_release_buffer(handle, *primary); */
 514 exit_sbh:
 515         /* ext4_journal_release_buffer(handle, *primary); */
 516 exit_dind:
 517         brelse(dind);
 518 exit_bh:
 519         brelse(*primary);
 520
 521         ext4_debug("leaving with error %d\n", err);
 522         return err;
 523 }
 524
 525 /*
 526  * Called when we are adding a new group which has a backup copy of each of
 527  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 528  * We need to add these reserved backup GDT blocks to the resize inode, so
 529  * that they are kept for future resizing and not allocated to files.
 530  *
 531  * Each reserved backup GDT block will go into a different indirect block.
 532  * The indirect blocks are actually the primary reserved GDT blocks,
 533  * so we know in advance what their block numbers are.  We only get the
 534  * double-indirect block to verify it is pointing to the primary reserved
 535  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 536  * backup GDT blocks are stored in their reserved primary GDT block.
 537  */
 538 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 539                               struct ext4_new_group_data *input)
 540 {
 541         struct super_block *sb = inode->i_sb;
 542         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 543         struct buffer_head **primary;
 544         struct buffer_head *dind;
 545         struct ext4_iloc iloc;
 546         ext4_fsblk_t blk;
 547         __le32 *data, *end;
 548         int gdbackups = 0;
 549         int res, i;
 550         int err;
 551
 552         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 553         if (!primary)
 554                 return -ENOMEM;
 555
 556         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 557         dind = sb_bread(sb, le32_to_cpu(*data));
 558         if (!dind) {
 559                 err = -EIO;
 560                 goto exit_free;
 561         }
 562
 563         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 564         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 565                                          EXT4_ADDR_PER_BLOCK(sb));
 566         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 567
 568         /* Get each reserved primary GDT block and verify it holds backups */
 569         for (res = 0; res < reserved_gdb; res++, blk++) {
 570                 if (le32_to_cpu(*data) != blk) {
 571                         ext4_warning(sb, __func__,
 572                                      "reserved block %llu"
 573                                      " not at offset %ld",
 574                                      blk,
 575                                      (long)(data - (__le32 *)dind->b_data));
 576                         err = -EINVAL;
 577                         goto exit_bh;
 578                 }
 579                 primary[res] = sb_bread(sb, blk);
 580                 if (!primary[res]) {
 581                         err = -EIO;
 582                         goto exit_bh;
 583                 }
 584                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 585                         brelse(primary[res]);
 586                         err = gdbackups;
 587                         goto exit_bh;
 588                 }
 589                 if (++data >= end)
 590                         data = (__le32 *)dind->b_data;
 591         }
 592
 593         for (i = 0; i < reserved_gdb; i++) {
 594                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 595                         /*
 596                         int j;
 597                         for (j = 0; j < i; j++)
 598                                 ext4_journal_release_buffer(handle, primary[j]);
 599                          */
 600                         goto exit_bh;
 601                 }
 602         }
 603
 604         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 605                 goto exit_bh;
 606
 607         /*
 608          * Finally we can add each of the reserved backup GDT blocks from
 609          * the new group to its reserved primary GDT block.
 610          */
 611         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
 612         for (i = 0; i < reserved_gdb; i++) {
 613                 int err2;
 614                 data = (__le32 *)primary[i]->b_data;
 615                 /* printk("reserving backup %lu[%u] = %lu\n",
 616                        primary[i]->b_blocknr, gdbackups,
 617                        blk + primary[i]->b_blocknr); */
 618                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 619                 err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
 620                 if (!err)
 621                         err = err2;
 622         }
 623         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 624         ext4_mark_iloc_dirty(handle, inode, &iloc);
 625
 626 exit_bh:
 627         while (--res >= 0)
 628                 brelse(primary[res]);
 629         brelse(dind);
 630
 631 exit_free:
 632         kfree(primary);
 633
 634         return err;
 635 }
 636
 637 /*
 638  * Update the backup copies of the ext4 metadata.  These don't need to be part
 639  * of the main resize transaction, because e2fsck will re-write them if there
 640  * is a problem (basically only OOM will cause a problem).  However, we
 641  * _should_ update the backups if possible, in case the primary gets trashed
 642  * for some reason and we need to run e2fsck from a backup superblock.  The
 643  * important part is that the new block and inode counts are in the backup
 644  * superblocks, and the location of the new group metadata in the GDT backups.
 645  *
 646  * We do not need lock_super() for this, because these blocks are not
 647  * otherwise touched by the filesystem code when it is mounted.  We don't
 648  * need to worry about last changing from sbi->s_groups_count, because the
 649  * worst that can happen is that we do not copy the full number of backups
 650  * at this time.  The resize which changed s_groups_count will backup again.
 651  */
 652 static void update_backups(struct super_block *sb,
 653                            int blk_off, char *data, int size)
 654 {
 655         struct ext4_sb_info *sbi = EXT4_SB(sb);
 656         const ext4_group_t last = sbi->s_groups_count;
 657         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 658         unsigned three = 1;
 659         unsigned five = 5;
 660         unsigned seven = 7;
 661         ext4_group_t group;
 662         int rest = sb->s_blocksize - size;
 663         handle_t *handle;
 664         int err = 0, err2;
 665
 666         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 667         if (IS_ERR(handle)) {
 668                 group = 1;
 669                 err = PTR_ERR(handle);
 670                 goto exit_err;
 671         }
 672
 673         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 674                 struct buffer_head *bh;
 675
 676                 /* Out of journal space, and can't get more - abort - so sad */
 677                 if (ext4_handle_valid(handle) &&
 678                     handle->h_buffer_credits == 0 &&
 679                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 680                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 681                         break;
 682
 683                 bh = sb_getblk(sb, group * bpg + blk_off);
 684                 if (!bh) {
 685                         err = -EIO;
 686                         break;
 687                 }
 688                 ext4_debug("update metadata backup %#04lx\n",
 689                           (unsigned long)bh->b_blocknr);
 690                 if ((err = ext4_journal_get_write_access(handle, bh)))
 691                         break;
 692                 lock_buffer(bh);
 693                 memcpy(bh->b_data, data, size);
 694                 if (rest)
 695                         memset(bh->b_data + size, 0, rest);
 696                 set_buffer_uptodate(bh);
 697                 unlock_buffer(bh);
 698                 ext4_handle_dirty_metadata(handle, NULL, bh);
 699                 brelse(bh);
 700         }
 701         if ((err2 = ext4_journal_stop(handle)) && !err)
 702                 err = err2;
 703
 704         /*
 705          * Ugh! Need to have e2fsck write the backup copies.  It is too
 706          * late to revert the resize, we shouldn't fail just because of
 707          * the backup copies (they are only needed in case of corruption).
 708          *
 709          * However, if we got here we have a journal problem too, so we
 710          * can't really start a transaction to mark the superblock.
 711          * Chicken out and just set the flag on the hope it will be written
 712          * to disk, and if not - we will simply wait until next fsck.
 713          */
 714 exit_err:
 715         if (err) {
 716                 ext4_warning(sb, __func__,
 717                              "can't update backup for group %u (err %d), "
 718                              "forcing fsck on next reboot", group, err);
 719                 sbi->s_mount_state &= ~EXT4_VALID_FS;
 720                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
 721                 mark_buffer_dirty(sbi->s_sbh);
 722         }
 723 }
 724
 725 /* Add group descriptor data to an existing or new group descriptor block.
 726  * Ensure we handle all possible error conditions _before_ we start modifying
 727  * the filesystem, because we cannot abort the transaction and not have it
 728  * write the data to disk.
 729  *
 730  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 731  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 732  *
 733  * We only need to hold the superblock lock while we are actually adding
 734  * in the new group's counts to the superblock.  Prior to that we have
 735  * not really "added" the group at all.  We re-check that we are still
 736  * adding in the last group in case things have changed since verifying.
 737  */
 738 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 739 {
 740         struct ext4_sb_info *sbi = EXT4_SB(sb);
 741         struct ext4_super_block *es = sbi->s_es;
 742         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 743                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 744         struct buffer_head *primary = NULL;
 745         struct ext4_group_desc *gdp;
 746         struct inode *inode = NULL;
 747         handle_t *handle;
 748         int gdb_off, gdb_num;
 749         int num_grp_locked = 0;
 750         int err, err2;
 751
 752         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 753         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
 754
 755         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
 756                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 757                 ext4_warning(sb, __func__,
 758                              "Can't resize non-sparse filesystem further");
 759                 return -EPERM;
 760         }
 761
 762         if (ext4_blocks_count(es) + input->blocks_count <
 763             ext4_blocks_count(es)) {
 764                 ext4_warning(sb, __func__, "blocks_count overflow");
 765                 return -EINVAL;
 766         }
 767
 768         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
 769             le32_to_cpu(es->s_inodes_count)) {
 770                 ext4_warning(sb, __func__, "inodes_count overflow");
 771                 return -EINVAL;
 772         }
 773
 774         if (reserved_gdb || gdb_off == 0) {
 775                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
 776                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)
 777                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
 778                         ext4_warning(sb, __func__,
 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, __func__,
 785                                      "Error opening resize inode");
 786                         return PTR_ERR(inode);
 787                 }
 788         }
 789
 790
 791         if ((err = verify_group_input(sb, input)))
 792                 goto exit_put;
 793
 794         if ((err = setup_new_group_blocks(sb, input)))
 795                 goto exit_put;
 796
 797         /*
 798          * We will always be modifying at least the superblock and a GDT
 799          * block.  If we are adding a group past the last current GDT block,
 800          * we will also modify the inode and the dindirect block.  If we
 801          * are adding a group with superblock/GDT backups  we will also
 802          * modify each of the reserved GDT dindirect blocks.
 803          */
 804         handle = ext4_journal_start_sb(sb,
 805                                        ext4_bg_has_super(sb, input->group) ?
 806                                        3 + reserved_gdb : 4);
 807         if (IS_ERR(handle)) {
 808                 err = PTR_ERR(handle);
 809                 goto exit_put;
 810         }
 811
 812         lock_super(sb);
 813         if (input->group != sbi->s_groups_count) {
 814                 ext4_warning(sb, __func__,
 815                              "multiple resizers run on filesystem!");
 816                 err = -EBUSY;
 817                 goto exit_journal;
 818         }
 819
 820         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
 821                 goto exit_journal;
 822
 823         /*
 824          * We will only either add reserved group blocks to a backup group
 825          * or remove reserved blocks for the first group in a new group block.
 826          * Doing both would be mean more complex code, and sane people don't
 827          * use non-sparse filesystems anymore.  This is already checked above.
 828          */
 829         if (gdb_off) {
 830                 primary = sbi->s_group_desc[gdb_num];
 831                 if ((err = ext4_journal_get_write_access(handle, primary)))
 832                         goto exit_journal;
 833
 834                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
 835                     (err = reserve_backup_gdb(handle, inode, input)))
 836                         goto exit_journal;
 837         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 838                 goto exit_journal;
 839
 840         /*
 841          * OK, now we've set up the new group.  Time to make it active.
 842          *
 843          * Current kernels don't lock all allocations via lock_super(),
 844          * so we have to be safe wrt. concurrent accesses the group
 845          * data.  So we need to be careful to set all of the relevant
 846          * group descriptor data etc. *before* we enable the group.
 847          *
 848          * The key field here is sbi->s_groups_count: as long as
 849          * that retains its old value, nobody is going to access the new
 850          * group.
 851          *
 852          * So first we update all the descriptor metadata for the new
 853          * group; then we update the total disk blocks count; then we
 854          * update the groups count to enable the group; then finally we
 855          * update the free space counts so that the system can start
 856          * using the new disk blocks.
 857          */
 858
 859         num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group);
 860         /* Update group descriptor block for new group */
 861         gdp = (struct ext4_group_desc *)((char *)primary->b_data +
 862                                          gdb_off * EXT4_DESC_SIZE(sb));
 863
 864         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
 865         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
 866         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
 867         ext4_free_blks_set(sb, gdp, input->free_blocks_count);
 868         ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
 869         gdp->bg_flags |= cpu_to_le16(EXT4_BG_INODE_ZEROED);
 870         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
 871
 872         /*
 873          * We can allocate memory for mb_alloc based on the new group
 874          * descriptor
 875          */
 876         err = ext4_mb_add_groupinfo(sb, input->group, gdp);
 877         if (err) {
 878                 ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 879                 goto exit_journal;
 880         }
 881
 882         /*
 883          * Make the new blocks and inodes valid next.  We do this before
 884          * increasing the group count so that once the group is enabled,
 885          * all of its blocks and inodes are already valid.
 886          *
 887          * We always allocate group-by-group, then block-by-block or
 888          * inode-by-inode within a group, so enabling these
 889          * blocks/inodes before the group is live won't actually let us
 890          * allocate the new space yet.
 891          */
 892         ext4_blocks_count_set(es, ext4_blocks_count(es) +
 893                 input->blocks_count);
 894         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb));
 895
 896         /*
 897          * We need to protect s_groups_count against other CPUs seeing
 898          * inconsistent state in the superblock.
 899          *
 900          * The precise rules we use are:
 901          *
 902          * * Writers of s_groups_count *must* hold lock_super
 903          * AND
 904          * * Writers must perform a smp_wmb() after updating all dependent
 905          *   data and before modifying the groups count
 906          *
 907          * * Readers must hold lock_super() over the access
 908          * OR
 909          * * Readers must perform an smp_rmb() after reading the groups count
 910          *   and before reading any dependent data.
 911          *
 912          * NB. These rules can be relaxed when checking the group count
 913          * while freeing data, as we can only allocate from a block
 914          * group after serialising against the group count, and we can
 915          * only then free after serialising in turn against that
 916          * allocation.
 917          */
 918         smp_wmb();
 919
 920         /* Update the global fs size fields */
 921         sbi->s_groups_count++;
 922         ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 923
 924         ext4_handle_dirty_metadata(handle, NULL, primary);
 925
 926         /* Update the reserved block counts only once the new group is
 927          * active. */
 928         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 929                 input->reserved_blocks);
 930
 931         /* Update the free space counts */
 932         percpu_counter_add(&sbi->s_freeblocks_counter,
 933                            input->free_blocks_count);
 934         percpu_counter_add(&sbi->s_freeinodes_counter,
 935                            EXT4_INODES_PER_GROUP(sb));
 936
 937         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 938                 ext4_group_t flex_group;
 939                 flex_group = ext4_flex_group(sbi, input->group);
 940                 sbi->s_flex_groups[flex_group].free_blocks +=
 941                         input->free_blocks_count;
 942                 sbi->s_flex_groups[flex_group].free_inodes +=
 943                         EXT4_INODES_PER_GROUP(sb);
 944         }
 945
 946         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 947         sb->s_dirt = 1;
 948
 949 exit_journal:
 950         unlock_super(sb);
 951         if ((err2 = ext4_journal_stop(handle)) && !err)
 952                 err = err2;
 953         if (!err) {
 954                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 955                                sizeof(struct ext4_super_block));
 956                 update_backups(sb, primary->b_blocknr, primary->b_data,
 957                                primary->b_size);
 958         }
 959 exit_put:
 960         iput(inode);
 961         return err;
 962 } /* ext4_group_add */
 963
 964 /*
 965  * Extend the filesystem to the new number of blocks specified.  This entry
 966  * point is only used to extend the current filesystem to the end of the last
 967  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 968  * for emergencies (because it has no dependencies on reserved blocks).
 969  *
 970  * If we _really_ wanted, we could use default values to call ext4_group_add()
 971  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 972  * GDT blocks are reserved to grow to the desired size.
 973  */
 974 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 975                       ext4_fsblk_t n_blocks_count)
 976 {
 977         ext4_fsblk_t o_blocks_count;
 978         ext4_group_t o_groups_count;
 979         ext4_grpblk_t last;
 980         ext4_grpblk_t add;
 981         struct buffer_head *bh;
 982         handle_t *handle;
 983         int err;
 984         ext4_group_t group;
 985
 986         /* We don't need to worry about locking wrt other resizers just
 987          * yet: we're going to revalidate es->s_blocks_count after
 988          * taking lock_super() below. */
 989         o_blocks_count = ext4_blocks_count(es);
 990         o_groups_count = EXT4_SB(sb)->s_groups_count;
 991
 992         if (test_opt(sb, DEBUG))
 993                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
 994                        o_blocks_count, n_blocks_count);
 995
 996         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 997                 return 0;
 998
 999         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1000                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
1001                         " too large to resize to %llu blocks safely\n",
1002                         sb->s_id, n_blocks_count);
1003                 if (sizeof(sector_t) < 8)
1004                         ext4_warning(sb, __func__, "CONFIG_LBD not enabled");
1005                 return -EINVAL;
1006         }
1007
1008         if (n_blocks_count < o_blocks_count) {
1009                 ext4_warning(sb, __func__,
1010                              "can't shrink FS - resize aborted");
1011                 return -EBUSY;
1012         }
1013
1014         /* Handle the remaining blocks in the last group only. */
1015         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1016
1017         if (last == 0) {
1018                 ext4_warning(sb, __func__,
1019                              "need to use ext2online to resize further");
1020                 return -EPERM;
1021         }
1022
1023         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1024
1025         if (o_blocks_count + add < o_blocks_count) {
1026                 ext4_warning(sb, __func__, "blocks_count overflow");
1027                 return -EINVAL;
1028         }
1029
1030         if (o_blocks_count + add > n_blocks_count)
1031                 add = n_blocks_count - o_blocks_count;
1032
1033         if (o_blocks_count + add < n_blocks_count)
1034                 ext4_warning(sb, __func__,
1035                              "will only finish group (%llu"
1036                              " blocks, %u new)",
1037                              o_blocks_count + add, add);
1038
1039         /* See if the device is actually as big as what was requested */
1040         bh = sb_bread(sb, o_blocks_count + add - 1);
1041         if (!bh) {
1042                 ext4_warning(sb, __func__,
1043                              "can't read last block, resize aborted");
1044                 return -ENOSPC;
1045         }
1046         brelse(bh);
1047
1048         /* We will update the superblock, one block bitmap, and
1049          * one group descriptor via ext4_free_blocks().
1050          */
1051         handle = ext4_journal_start_sb(sb, 3);
1052         if (IS_ERR(handle)) {
1053                 err = PTR_ERR(handle);
1054                 ext4_warning(sb, __func__, "error %d on journal start", err);
1055                 goto exit_put;
1056         }
1057
1058         lock_super(sb);
1059         if (o_blocks_count != ext4_blocks_count(es)) {
1060                 ext4_warning(sb, __func__,
1061                              "multiple resizers run on filesystem!");
1062                 unlock_super(sb);
1063                 ext4_journal_stop(handle);
1064                 err = -EBUSY;
1065                 goto exit_put;
1066         }
1067
1068         if ((err = ext4_journal_get_write_access(handle,
1069                                                  EXT4_SB(sb)->s_sbh))) {
1070                 ext4_warning(sb, __func__,
1071                              "error %d on journal write access", err);
1072                 unlock_super(sb);
1073                 ext4_journal_stop(handle);
1074                 goto exit_put;
1075         }
1076         ext4_blocks_count_set(es, o_blocks_count + add);
1077         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
1078         sb->s_dirt = 1;
1079         unlock_super(sb);
1080         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1081                    o_blocks_count + add);
1082         /* We add the blocks to the bitmap and set the group need init bit */
1083         ext4_add_groupblocks(handle, sb, o_blocks_count, add);
1084         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1085                    o_blocks_count + add);
1086         if ((err = ext4_journal_stop(handle)))
1087                 goto exit_put;
1088
1089         if (test_opt(sb, DEBUG))
1090                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1091                        ext4_blocks_count(es));
1092         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1093                        sizeof(struct ext4_super_block));
1094 exit_put:
1095         return err;
1096 } /* ext4_group_extend */