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 %lu 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 (handle->h_buffer_credits >= 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_journal_dirty_metadata(handle, 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_journal_dirty_metadata(handle, 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_journal_dirty_metadata(handle, 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, EXT4_BLOCKS_PER_GROUP(sb),
 288                         bh->b_data);
 289         ext4_journal_dirty_metadata(handle, bh);
 290         brelse(bh);
 291
 292         /* Mark unused entries in inode bitmap used */
 293         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
 294                    input->inode_bitmap, input->inode_bitmap - start);
 295         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 296                 err = PTR_ERR(bh);
 297                 goto exit_journal;
 298         }
 299
 300         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), EXT4_BLOCKS_PER_GROUP(sb),
 301                         bh->b_data);
 302         ext4_journal_dirty_metadata(handle, bh);
 303 exit_bh:
 304         brelse(bh);
 305
 306 exit_journal:
 307         unlock_super(sb);
 308         if ((err2 = ext4_journal_stop(handle)) && !err)
 309                 err = err2;
 310
 311         return err;
 312 }
 313
 314 /*
 315  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 316  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 317  * calling this for the first time.  In a sparse filesystem it will be the
 318  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 319  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 320  */
 321 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 322                                   unsigned *five, unsigned *seven)
 323 {
 324         unsigned *min = three;
 325         int mult = 3;
 326         unsigned ret;
 327
 328         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 329                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 330                 ret = *min;
 331                 *min += 1;
 332                 return ret;
 333         }
 334
 335         if (*five < *min) {
 336                 min = five;
 337                 mult = 5;
 338         }
 339         if (*seven < *min) {
 340                 min = seven;
 341                 mult = 7;
 342         }
 343
 344         ret = *min;
 345         *min *= mult;
 346
 347         return ret;
 348 }
 349
 350 /*
 351  * Check that all of the backup GDT blocks are held in the primary GDT block.
 352  * It is assumed that they are stored in group order.  Returns the number of
 353  * groups in current filesystem that have BACKUPS, or -ve error code.
 354  */
 355 static int verify_reserved_gdb(struct super_block *sb,
 356                                struct buffer_head *primary)
 357 {
 358         const ext4_fsblk_t blk = primary->b_blocknr;
 359         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
 360         unsigned three = 1;
 361         unsigned five = 5;
 362         unsigned seven = 7;
 363         unsigned grp;
 364         __le32 *p = (__le32 *)primary->b_data;
 365         int gdbackups = 0;
 366
 367         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 368                 if (le32_to_cpu(*p++) !=
 369                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 370                         ext4_warning(sb, __func__,
 371                                      "reserved GDT %llu"
 372                                      " missing grp %d (%llu)",
 373                                      blk, grp,
 374                                      grp *
 375                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 376                                      blk);
 377                         return -EINVAL;
 378                 }
 379                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 380                         return -EFBIG;
 381         }
 382
 383         return gdbackups;
 384 }
 385
 386 /*
 387  * Called when we need to bring a reserved group descriptor table block into
 388  * use from the resize inode.  The primary copy of the new GDT block currently
 389  * is an indirect block (under the double indirect block in the resize inode).
 390  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 391  * block, in group order.  Even though we know all the block numbers we need,
 392  * we check to ensure that the resize inode has actually reserved these blocks.
 393  *
 394  * Don't need to update the block bitmaps because the blocks are still in use.
 395  *
 396  * We get all of the error cases out of the way, so that we are sure to not
 397  * fail once we start modifying the data on disk, because JBD has no rollback.
 398  */
 399 static int add_new_gdb(handle_t *handle, struct inode *inode,
 400                        struct ext4_new_group_data *input,
 401                        struct buffer_head **primary)
 402 {
 403         struct super_block *sb = inode->i_sb;
 404         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 405         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 406         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 407         struct buffer_head **o_group_desc, **n_group_desc;
 408         struct buffer_head *dind;
 409         int gdbackups;
 410         struct ext4_iloc iloc;
 411         __le32 *data;
 412         int err;
 413
 414         if (test_opt(sb, DEBUG))
 415                 printk(KERN_DEBUG
 416                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 417                        gdb_num);
 418
 419         /*
 420          * If we are not using the primary superblock/GDT copy don't resize,
 421          * because the user tools have no way of handling this.  Probably a
 422          * bad time to do it anyways.
 423          */
 424         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 425             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 426                 ext4_warning(sb, __func__,
 427                         "won't resize using backup superblock at %llu",
 428                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 429                 return -EPERM;
 430         }
 431
 432         *primary = sb_bread(sb, gdblock);
 433         if (!*primary)
 434                 return -EIO;
 435
 436         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 437                 err = gdbackups;
 438                 goto exit_bh;
 439         }
 440
 441         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 442         dind = sb_bread(sb, le32_to_cpu(*data));
 443         if (!dind) {
 444                 err = -EIO;
 445                 goto exit_bh;
 446         }
 447
 448         data = (__le32 *)dind->b_data;
 449         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 450                 ext4_warning(sb, __func__,
 451                              "new group %u GDT block %llu not reserved",
 452                              input->group, gdblock);
 453                 err = -EINVAL;
 454                 goto exit_dind;
 455         }
 456
 457         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
 458                 goto exit_dind;
 459
 460         if ((err = ext4_journal_get_write_access(handle, *primary)))
 461                 goto exit_sbh;
 462
 463         if ((err = ext4_journal_get_write_access(handle, dind)))
 464                 goto exit_primary;
 465
 466         /* ext4_reserve_inode_write() gets a reference on the iloc */
 467         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 468                 goto exit_dindj;
 469
 470         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 471                         GFP_NOFS);
 472         if (!n_group_desc) {
 473                 err = -ENOMEM;
 474                 ext4_warning(sb, __func__,
 475                               "not enough memory for %lu groups", gdb_num + 1);
 476                 goto exit_inode;
 477         }
 478
 479         /*
 480          * Finally, we have all of the possible failures behind us...
 481          *
 482          * Remove new GDT block from inode double-indirect block and clear out
 483          * the new GDT block for use (which also "frees" the backup GDT blocks
 484          * from the reserved inode).  We don't need to change the bitmaps for
 485          * these blocks, because they are marked as in-use from being in the
 486          * reserved inode, and will become GDT blocks (primary and backup).
 487          */
 488         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 489         ext4_journal_dirty_metadata(handle, dind);
 490         brelse(dind);
 491         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 492         ext4_mark_iloc_dirty(handle, inode, &iloc);
 493         memset((*primary)->b_data, 0, sb->s_blocksize);
 494         ext4_journal_dirty_metadata(handle, *primary);
 495
 496         o_group_desc = EXT4_SB(sb)->s_group_desc;
 497         memcpy(n_group_desc, o_group_desc,
 498                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 499         n_group_desc[gdb_num] = *primary;
 500         EXT4_SB(sb)->s_group_desc = n_group_desc;
 501         EXT4_SB(sb)->s_gdb_count++;
 502         kfree(o_group_desc);
 503
 504         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 505         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 506
 507         return 0;
 508
 509 exit_inode:
 510         //ext4_journal_release_buffer(handle, iloc.bh);
 511         brelse(iloc.bh);
 512 exit_dindj:
 513         //ext4_journal_release_buffer(handle, dind);
 514 exit_primary:
 515         //ext4_journal_release_buffer(handle, *primary);
 516 exit_sbh:
 517         //ext4_journal_release_buffer(handle, *primary);
 518 exit_dind:
 519         brelse(dind);
 520 exit_bh:
 521         brelse(*primary);
 522
 523         ext4_debug("leaving with error %d\n", err);
 524         return err;
 525 }
 526
 527 /*
 528  * Called when we are adding a new group which has a backup copy of each of
 529  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 530  * We need to add these reserved backup GDT blocks to the resize inode, so
 531  * that they are kept for future resizing and not allocated to files.
 532  *
 533  * Each reserved backup GDT block will go into a different indirect block.
 534  * The indirect blocks are actually the primary reserved GDT blocks,
 535  * so we know in advance what their block numbers are.  We only get the
 536  * double-indirect block to verify it is pointing to the primary reserved
 537  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 538  * backup GDT blocks are stored in their reserved primary GDT block.
 539  */
 540 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 541                               struct ext4_new_group_data *input)
 542 {
 543         struct super_block *sb = inode->i_sb;
 544         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 545         struct buffer_head **primary;
 546         struct buffer_head *dind;
 547         struct ext4_iloc iloc;
 548         ext4_fsblk_t blk;
 549         __le32 *data, *end;
 550         int gdbackups = 0;
 551         int res, i;
 552         int err;
 553
 554         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 555         if (!primary)
 556                 return -ENOMEM;
 557
 558         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 559         dind = sb_bread(sb, le32_to_cpu(*data));
 560         if (!dind) {
 561                 err = -EIO;
 562                 goto exit_free;
 563         }
 564
 565         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 566         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 567                                          EXT4_ADDR_PER_BLOCK(sb));
 568         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 569
 570         /* Get each reserved primary GDT block and verify it holds backups */
 571         for (res = 0; res < reserved_gdb; res++, blk++) {
 572                 if (le32_to_cpu(*data) != blk) {
 573                         ext4_warning(sb, __func__,
 574                                      "reserved block %llu"
 575                                      " not at offset %ld",
 576                                      blk,
 577                                      (long)(data - (__le32 *)dind->b_data));
 578                         err = -EINVAL;
 579                         goto exit_bh;
 580                 }
 581                 primary[res] = sb_bread(sb, blk);
 582                 if (!primary[res]) {
 583                         err = -EIO;
 584                         goto exit_bh;
 585                 }
 586                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 587                         brelse(primary[res]);
 588                         err = gdbackups;
 589                         goto exit_bh;
 590                 }
 591                 if (++data >= end)
 592                         data = (__le32 *)dind->b_data;
 593         }
 594
 595         for (i = 0; i < reserved_gdb; i++) {
 596                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 597                         /*
 598                         int j;
 599                         for (j = 0; j < i; j++)
 600                                 ext4_journal_release_buffer(handle, primary[j]);
 601                          */
 602                         goto exit_bh;
 603                 }
 604         }
 605
 606         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 607                 goto exit_bh;
 608
 609         /*
 610          * Finally we can add each of the reserved backup GDT blocks from
 611          * the new group to its reserved primary GDT block.
 612          */
 613         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
 614         for (i = 0; i < reserved_gdb; i++) {
 615                 int err2;
 616                 data = (__le32 *)primary[i]->b_data;
 617                 /* printk("reserving backup %lu[%u] = %lu\n",
 618                        primary[i]->b_blocknr, gdbackups,
 619                        blk + primary[i]->b_blocknr); */
 620                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 621                 err2 = ext4_journal_dirty_metadata(handle, primary[i]);
 622                 if (!err)
 623                         err = err2;
 624         }
 625         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 626         ext4_mark_iloc_dirty(handle, inode, &iloc);
 627
 628 exit_bh:
 629         while (--res >= 0)
 630                 brelse(primary[res]);
 631         brelse(dind);
 632
 633 exit_free:
 634         kfree(primary);
 635
 636         return err;
 637 }
 638
 639 /*
 640  * Update the backup copies of the ext4 metadata.  These don't need to be part
 641  * of the main resize transaction, because e2fsck will re-write them if there
 642  * is a problem (basically only OOM will cause a problem).  However, we
 643  * _should_ update the backups if possible, in case the primary gets trashed
 644  * for some reason and we need to run e2fsck from a backup superblock.  The
 645  * important part is that the new block and inode counts are in the backup
 646  * superblocks, and the location of the new group metadata in the GDT backups.
 647  *
 648  * We do not need lock_super() for this, because these blocks are not
 649  * otherwise touched by the filesystem code when it is mounted.  We don't
 650  * need to worry about last changing from sbi->s_groups_count, because the
 651  * worst that can happen is that we do not copy the full number of backups
 652  * at this time.  The resize which changed s_groups_count will backup again.
 653  */
 654 static void update_backups(struct super_block *sb,
 655                            int blk_off, char *data, int size)
 656 {
 657         struct ext4_sb_info *sbi = EXT4_SB(sb);
 658         const ext4_group_t last = sbi->s_groups_count;
 659         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 660         unsigned three = 1;
 661         unsigned five = 5;
 662         unsigned seven = 7;
 663         ext4_group_t group;
 664         int rest = sb->s_blocksize - size;
 665         handle_t *handle;
 666         int err = 0, err2;
 667
 668         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 669         if (IS_ERR(handle)) {
 670                 group = 1;
 671                 err = PTR_ERR(handle);
 672                 goto exit_err;
 673         }
 674
 675         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 676                 struct buffer_head *bh;
 677
 678                 /* Out of journal space, and can't get more - abort - so sad */
 679                 if (handle->h_buffer_credits == 0 &&
 680                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 681                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 682                         break;
 683
 684                 bh = sb_getblk(sb, group * bpg + blk_off);
 685                 if (!bh) {
 686                         err = -EIO;
 687                         break;
 688                 }
 689                 ext4_debug("update metadata backup %#04lx\n",
 690                           (unsigned long)bh->b_blocknr);
 691                 if ((err = ext4_journal_get_write_access(handle, bh)))
 692                         break;
 693                 lock_buffer(bh);
 694                 memcpy(bh->b_data, data, size);
 695                 if (rest)
 696                         memset(bh->b_data + size, 0, rest);
 697                 set_buffer_uptodate(bh);
 698                 unlock_buffer(bh);
 699                 ext4_journal_dirty_metadata(handle, bh);
 700                 brelse(bh);
 701         }
 702         if ((err2 = ext4_journal_stop(handle)) && !err)
 703                 err = err2;
 704
 705         /*
 706          * Ugh! Need to have e2fsck write the backup copies.  It is too
 707          * late to revert the resize, we shouldn't fail just because of
 708          * the backup copies (they are only needed in case of corruption).
 709          *
 710          * However, if we got here we have a journal problem too, so we
 711          * can't really start a transaction to mark the superblock.
 712          * Chicken out and just set the flag on the hope it will be written
 713          * to disk, and if not - we will simply wait until next fsck.
 714          */
 715 exit_err:
 716         if (err) {
 717                 ext4_warning(sb, __func__,
 718                              "can't update backup for group %lu (err %d), "
 719                              "forcing fsck on next reboot", group, err);
 720                 sbi->s_mount_state &= ~EXT4_VALID_FS;
 721                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
 722                 mark_buffer_dirty(sbi->s_sbh);
 723         }
 724 }
 725
 726 /* Add group descriptor data to an existing or new group descriptor block.
 727  * Ensure we handle all possible error conditions _before_ we start modifying
 728  * the filesystem, because we cannot abort the transaction and not have it
 729  * write the data to disk.
 730  *
 731  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 732  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 733  *
 734  * We only need to hold the superblock lock while we are actually adding
 735  * in the new group's counts to the superblock.  Prior to that we have
 736  * not really "added" the group at all.  We re-check that we are still
 737  * adding in the last group in case things have changed since verifying.
 738  */
 739 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 740 {
 741         struct ext4_sb_info *sbi = EXT4_SB(sb);
 742         struct ext4_super_block *es = sbi->s_es;
 743         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 744                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 745         struct buffer_head *primary = NULL;
 746         struct ext4_group_desc *gdp;
 747         struct inode *inode = NULL;
 748         handle_t *handle;
 749         int gdb_off, gdb_num;
 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\n");
 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\n");
 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                         ext4_warning(sb, __func__,
 778                                      "No reserved GDT blocks, can't resize");
 779                         return -EPERM;
 780                 }
 781                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
 782                 if (IS_ERR(inode)) {
 783                         ext4_warning(sb, __func__,
 784                                      "Error opening resize inode");
 785                         return PTR_ERR(inode);
 786                 }
 787         }
 788
 789         if ((err = verify_group_input(sb, input)))
 790                 goto exit_put;
 791
 792         if ((err = setup_new_group_blocks(sb, input)))
 793                 goto exit_put;
 794
 795         /*
 796          * We will always be modifying at least the superblock and a GDT
 797          * block.  If we are adding a group past the last current GDT block,
 798          * we will also modify the inode and the dindirect block.  If we
 799          * are adding a group with superblock/GDT backups  we will also
 800          * modify each of the reserved GDT dindirect blocks.
 801          */
 802         handle = ext4_journal_start_sb(sb,
 803                                        ext4_bg_has_super(sb, input->group) ?
 804                                        3 + reserved_gdb : 4);
 805         if (IS_ERR(handle)) {
 806                 err = PTR_ERR(handle);
 807                 goto exit_put;
 808         }
 809
 810         lock_super(sb);
 811         if (input->group != sbi->s_groups_count) {
 812                 ext4_warning(sb, __func__,
 813                              "multiple resizers run on filesystem!");
 814                 err = -EBUSY;
 815                 goto exit_journal;
 816         }
 817
 818         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
 819                 goto exit_journal;
 820
 821         /*
 822          * We will only either add reserved group blocks to a backup group
 823          * or remove reserved blocks for the first group in a new group block.
 824          * Doing both would be mean more complex code, and sane people don't
 825          * use non-sparse filesystems anymore.  This is already checked above.
 826          */
 827         if (gdb_off) {
 828                 primary = sbi->s_group_desc[gdb_num];
 829                 if ((err = ext4_journal_get_write_access(handle, primary)))
 830                         goto exit_journal;
 831
 832                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
 833                     (err = reserve_backup_gdb(handle, inode, input)))
 834                         goto exit_journal;
 835         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 836                 goto exit_journal;
 837
 838         /*
 839          * OK, now we've set up the new group.  Time to make it active.
 840          *
 841          * Current kernels don't lock all allocations via lock_super(),
 842          * so we have to be safe wrt. concurrent accesses the group
 843          * data.  So we need to be careful to set all of the relevant
 844          * group descriptor data etc. *before* we enable the group.
 845          *
 846          * The key field here is sbi->s_groups_count: as long as
 847          * that retains its old value, nobody is going to access the new
 848          * group.
 849          *
 850          * So first we update all the descriptor metadata for the new
 851          * group; then we update the total disk blocks count; then we
 852          * update the groups count to enable the group; then finally we
 853          * update the free space counts so that the system can start
 854          * using the new disk blocks.
 855          */
 856
 857         /* Update group descriptor block for new group */
 858         gdp = (struct ext4_group_desc *)((char *)primary->b_data +
 859                                          gdb_off * EXT4_DESC_SIZE(sb));
 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         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb));
 881
 882         /*
 883          * We need to protect s_groups_count against other CPUs seeing
 884          * inconsistent state in the superblock.
 885          *
 886          * The precise rules we use are:
 887          *
 888          * * Writers of s_groups_count *must* hold lock_super
 889          * AND
 890          * * Writers must perform a smp_wmb() after updating all dependent
 891          *   data and before modifying the groups count
 892          *
 893          * * Readers must hold lock_super() over the access
 894          * OR
 895          * * Readers must perform an smp_rmb() after reading the groups count
 896          *   and before reading any dependent data.
 897          *
 898          * NB. These rules can be relaxed when checking the group count
 899          * while freeing data, as we can only allocate from a block
 900          * group after serialising against the group count, and we can
 901          * only then free after serialising in turn against that
 902          * allocation.
 903          */
 904         smp_wmb();
 905
 906         /* Update the global fs size fields */
 907         sbi->s_groups_count++;
 908
 909         ext4_journal_dirty_metadata(handle, primary);
 910
 911         /* Update the reserved block counts only once the new group is
 912          * active. */
 913         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 914                 input->reserved_blocks);
 915
 916         /* Update the free space counts */
 917         percpu_counter_add(&sbi->s_freeblocks_counter,
 918                            input->free_blocks_count);
 919         percpu_counter_add(&sbi->s_freeinodes_counter,
 920                            EXT4_INODES_PER_GROUP(sb));
 921
 922         ext4_journal_dirty_metadata(handle, sbi->s_sbh);
 923         sb->s_dirt = 1;
 924
 925 exit_journal:
 926         unlock_super(sb);
 927         if ((err2 = ext4_journal_stop(handle)) && !err)
 928                 err = err2;
 929         if (!err) {
 930                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 931                                sizeof(struct ext4_super_block));
 932                 update_backups(sb, primary->b_blocknr, primary->b_data,
 933                                primary->b_size);
 934         }
 935 exit_put:
 936         iput(inode);
 937         return err;
 938 } /* ext4_group_add */
 939
 940 /* Extend the filesystem to the new number of blocks specified.  This entry
 941  * point is only used to extend the current filesystem to the end of the last
 942  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 943  * for emergencies (because it has no dependencies on reserved blocks).
 944  *
 945  * If we _really_ wanted, we could use default values to call ext4_group_add()
 946  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 947  * GDT blocks are reserved to grow to the desired size.
 948  */
 949 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 950                       ext4_fsblk_t n_blocks_count)
 951 {
 952         ext4_fsblk_t o_blocks_count;
 953         ext4_group_t o_groups_count;
 954         ext4_grpblk_t last;
 955         ext4_grpblk_t add;
 956         struct buffer_head * bh;
 957         handle_t *handle;
 958         int err;
 959         unsigned long freed_blocks;
 960
 961         /* We don't need to worry about locking wrt other resizers just
 962          * yet: we're going to revalidate es->s_blocks_count after
 963          * taking lock_super() below. */
 964         o_blocks_count = ext4_blocks_count(es);
 965         o_groups_count = EXT4_SB(sb)->s_groups_count;
 966
 967         if (test_opt(sb, DEBUG))
 968                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
 969                        o_blocks_count, n_blocks_count);
 970
 971         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 972                 return 0;
 973
 974         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
 975                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
 976                         " too large to resize to %llu blocks safely\n",
 977                         sb->s_id, n_blocks_count);
 978                 if (sizeof(sector_t) < 8)
 979                         ext4_warning(sb, __func__,
 980                         "CONFIG_LBD not enabled\n");
 981                 return -EINVAL;
 982         }
 983
 984         if (n_blocks_count < o_blocks_count) {
 985                 ext4_warning(sb, __func__,
 986                              "can't shrink FS - resize aborted");
 987                 return -EBUSY;
 988         }
 989
 990         /* Handle the remaining blocks in the last group only. */
 991         ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
 992
 993         if (last == 0) {
 994                 ext4_warning(sb, __func__,
 995                              "need to use ext2online to resize further");
 996                 return -EPERM;
 997         }
 998
 999         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1000
1001         if (o_blocks_count + add < o_blocks_count) {
1002                 ext4_warning(sb, __func__, "blocks_count overflow");
1003                 return -EINVAL;
1004         }
1005
1006         if (o_blocks_count + add > n_blocks_count)
1007                 add = n_blocks_count - o_blocks_count;
1008
1009         if (o_blocks_count + add < n_blocks_count)
1010                 ext4_warning(sb, __func__,
1011                              "will only finish group (%llu"
1012                              " blocks, %u new)",
1013                              o_blocks_count + add, add);
1014
1015         /* See if the device is actually as big as what was requested */
1016         bh = sb_bread(sb, o_blocks_count + add -1);
1017         if (!bh) {
1018                 ext4_warning(sb, __func__,
1019                              "can't read last block, resize aborted");
1020                 return -ENOSPC;
1021         }
1022         brelse(bh);
1023
1024         /* We will update the superblock, one block bitmap, and
1025          * one group descriptor via ext4_free_blocks().
1026          */
1027         handle = ext4_journal_start_sb(sb, 3);
1028         if (IS_ERR(handle)) {
1029                 err = PTR_ERR(handle);
1030                 ext4_warning(sb, __func__, "error %d on journal start", err);
1031                 goto exit_put;
1032         }
1033
1034         lock_super(sb);
1035         if (o_blocks_count != ext4_blocks_count(es)) {
1036                 ext4_warning(sb, __func__,
1037                              "multiple resizers run on filesystem!");
1038                 unlock_super(sb);
1039                 ext4_journal_stop(handle);
1040                 err = -EBUSY;
1041                 goto exit_put;
1042         }
1043
1044         if ((err = ext4_journal_get_write_access(handle,
1045                                                  EXT4_SB(sb)->s_sbh))) {
1046                 ext4_warning(sb, __func__,
1047                              "error %d on journal write access", err);
1048                 unlock_super(sb);
1049                 ext4_journal_stop(handle);
1050                 goto exit_put;
1051         }
1052         ext4_blocks_count_set(es, o_blocks_count + add);
1053         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
1054         sb->s_dirt = 1;
1055         unlock_super(sb);
1056         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1057                    o_blocks_count + add);
1058         ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1059         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1060                    o_blocks_count + add);
1061         if ((err = ext4_journal_stop(handle)))
1062                 goto exit_put;
1063         if (test_opt(sb, DEBUG))
1064                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1065                        ext4_blocks_count(es));
1066         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1067                        sizeof(struct ext4_super_block));
1068 exit_put:
1069         return err;
1070 } /* ext4_group_extend */