fs/ext3/resize.c

   1 /*
   2  *  linux/fs/ext3/resize.c
   3  *
   4  * Support for resizing an ext3 filesystem while it is mounted.
   5  *
   6  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
   7  *
   8  * This could probably be made into a module, because it is not often in use.
   9  */
  10
  11
  12 #define EXT3FS_DEBUG
  13
  14 #include "ext3.h"
  15
  16
  17 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  18 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  19
  20 static int verify_group_input(struct super_block *sb,
  21                               struct ext3_new_group_data *input)
  22 {
  23         struct ext3_sb_info *sbi = EXT3_SB(sb);
  24         struct ext3_super_block *es = sbi->s_es;
  25         ext3_fsblk_t start = le32_to_cpu(es->s_blocks_count);
  26         ext3_fsblk_t end = start + input->blocks_count;
  27         unsigned group = input->group;
  28         ext3_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  29         unsigned overhead = ext3_bg_has_super(sb, group) ?
  30                 (1 + ext3_bg_num_gdb(sb, group) +
  31                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  32         ext3_fsblk_t metaend = start + overhead;
  33         struct buffer_head *bh = NULL;
  34         ext3_grpblk_t free_blocks_count;
  35         int err = -EINVAL;
  36
  37         input->free_blocks_count = free_blocks_count =
  38                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  39
  40         if (test_opt(sb, DEBUG))
  41                 printk(KERN_DEBUG "EXT3-fs: adding %s group %u: %u blocks "
  42                        "(%d free, %u reserved)\n",
  43                        ext3_bg_has_super(sb, input->group) ? "normal" :
  44                        "no-super", input->group, input->blocks_count,
  45                        free_blocks_count, input->reserved_blocks);
  46
  47         if (group != sbi->s_groups_count)
  48                 ext3_warning(sb, __func__,
  49                              "Cannot add at group %u (only %lu groups)",
  50                              input->group, sbi->s_groups_count);
  51         else if ((start - le32_to_cpu(es->s_first_data_block)) %
  52                  EXT3_BLOCKS_PER_GROUP(sb))
  53                 ext3_warning(sb, __func__, "Last group not full");
  54         else if (input->reserved_blocks > input->blocks_count / 5)
  55                 ext3_warning(sb, __func__, "Reserved blocks too high (%u)",
  56                              input->reserved_blocks);
  57         else if (free_blocks_count < 0)
  58                 ext3_warning(sb, __func__, "Bad blocks count %u",
  59                              input->blocks_count);
  60         else if (!(bh = sb_bread(sb, end - 1)))
  61                 ext3_warning(sb, __func__,
  62                              "Cannot read last block ("E3FSBLK")",
  63                              end - 1);
  64         else if (outside(input->block_bitmap, start, end))
  65                 ext3_warning(sb, __func__,
  66                              "Block bitmap not in group (block %u)",
  67                              input->block_bitmap);
  68         else if (outside(input->inode_bitmap, start, end))
  69                 ext3_warning(sb, __func__,
  70                              "Inode bitmap not in group (block %u)",
  71                              input->inode_bitmap);
  72         else if (outside(input->inode_table, start, end) ||
  73                  outside(itend - 1, start, end))
  74                 ext3_warning(sb, __func__,
  75                              "Inode table not in group (blocks %u-"E3FSBLK")",
  76                              input->inode_table, itend - 1);
  77         else if (input->inode_bitmap == input->block_bitmap)
  78                 ext3_warning(sb, __func__,
  79                              "Block bitmap same as inode bitmap (%u)",
  80                              input->block_bitmap);
  81         else if (inside(input->block_bitmap, input->inode_table, itend))
  82                 ext3_warning(sb, __func__,
  83                              "Block bitmap (%u) in inode table (%u-"E3FSBLK")",
  84                              input->block_bitmap, input->inode_table, itend-1);
  85         else if (inside(input->inode_bitmap, input->inode_table, itend))
  86                 ext3_warning(sb, __func__,
  87                              "Inode bitmap (%u) in inode table (%u-"E3FSBLK")",
  88                              input->inode_bitmap, input->inode_table, itend-1);
  89         else if (inside(input->block_bitmap, start, metaend))
  90                 ext3_warning(sb, __func__,
  91                              "Block bitmap (%u) in GDT table"
  92                              " ("E3FSBLK"-"E3FSBLK")",
  93                              input->block_bitmap, start, metaend - 1);
  94         else if (inside(input->inode_bitmap, start, metaend))
  95                 ext3_warning(sb, __func__,
  96                              "Inode bitmap (%u) in GDT table"
  97                              " ("E3FSBLK"-"E3FSBLK")",
  98                              input->inode_bitmap, start, metaend - 1);
  99         else if (inside(input->inode_table, start, metaend) ||
 100                  inside(itend - 1, start, metaend))
 101                 ext3_warning(sb, __func__,
 102                              "Inode table (%u-"E3FSBLK") overlaps"
 103                              "GDT table ("E3FSBLK"-"E3FSBLK")",
 104                              input->inode_table, itend - 1, start, metaend - 1);
 105         else
 106                 err = 0;
 107         brelse(bh);
 108
 109         return err;
 110 }
 111
 112 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 113                                   ext3_fsblk_t blk)
 114 {
 115         struct buffer_head *bh;
 116         int err;
 117
 118         bh = sb_getblk(sb, blk);
 119         if (unlikely(!bh))
 120                 return ERR_PTR(-ENOMEM);
 121         if ((err = ext3_journal_get_write_access(handle, bh))) {
 122                 brelse(bh);
 123                 bh = ERR_PTR(err);
 124         } else {
 125                 lock_buffer(bh);
 126                 memset(bh->b_data, 0, sb->s_blocksize);
 127                 set_buffer_uptodate(bh);
 128                 unlock_buffer(bh);
 129         }
 130
 131         return bh;
 132 }
 133
 134 /*
 135  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 136  * need to use it within a single byte (to ensure we get endianness right).
 137  * We can use memset for the rest of the bitmap as there are no other users.
 138  */
 139 static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 140 {
 141         int i;
 142
 143         if (start_bit >= end_bit)
 144                 return;
 145
 146         ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 147         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 148                 ext3_set_bit(i, bitmap);
 149         if (i < end_bit)
 150                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 151 }
 152
 153 /*
 154  * If we have fewer than thresh credits, extend by EXT3_MAX_TRANS_DATA.
 155  * If that fails, restart the transaction & regain write access for the
 156  * buffer head which is used for block_bitmap modifications.
 157  */
 158 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 159                                          struct buffer_head *bh)
 160 {
 161         int err;
 162
 163         if (handle->h_buffer_credits >= thresh)
 164                 return 0;
 165
 166         err = ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA);
 167         if (err < 0)
 168                 return err;
 169         if (err) {
 170                 err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA);
 171                 if (err)
 172                         return err;
 173                 err = ext3_journal_get_write_access(handle, bh);
 174                 if (err)
 175                         return err;
 176         }
 177
 178         return 0;
 179 }
 180
 181 /*
 182  * Set up the block and inode bitmaps, and the inode table for the new group.
 183  * This doesn't need to be part of the main transaction, since we are only
 184  * changing blocks outside the actual filesystem.  We still do journaling to
 185  * ensure the recovery is correct in case of a failure just after resize.
 186  * If any part of this fails, we simply abort the resize.
 187  */
 188 static int setup_new_group_blocks(struct super_block *sb,
 189                                   struct ext3_new_group_data *input)
 190 {
 191         struct ext3_sb_info *sbi = EXT3_SB(sb);
 192         ext3_fsblk_t start = ext3_group_first_block_no(sb, input->group);
 193         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 194                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 195         unsigned long gdblocks = ext3_bg_num_gdb(sb, input->group);
 196         struct buffer_head *bh;
 197         handle_t *handle;
 198         ext3_fsblk_t block;
 199         ext3_grpblk_t bit;
 200         int i;
 201         int err = 0, err2;
 202
 203         /* This transaction may be extended/restarted along the way */
 204         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 205
 206         if (IS_ERR(handle))
 207                 return PTR_ERR(handle);
 208
 209         mutex_lock(&sbi->s_resize_lock);
 210         if (input->group != sbi->s_groups_count) {
 211                 err = -EBUSY;
 212                 goto exit_journal;
 213         }
 214
 215         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 216                 err = PTR_ERR(bh);
 217                 goto exit_journal;
 218         }
 219
 220         if (ext3_bg_has_super(sb, input->group)) {
 221                 ext3_debug("mark backup superblock %#04lx (+0)\n", start);
 222                 ext3_set_bit(0, bh->b_data);
 223         }
 224
 225         /* Copy all of the GDT blocks into the backup in this group */
 226         for (i = 0, bit = 1, block = start + 1;
 227              i < gdblocks; i++, block++, bit++) {
 228                 struct buffer_head *gdb;
 229
 230                 ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
 231
 232                 err = extend_or_restart_transaction(handle, 1, bh);
 233                 if (err)
 234                         goto exit_bh;
 235
 236                 gdb = sb_getblk(sb, block);
 237                 if (unlikely(!gdb)) {
 238                         err = -ENOMEM;
 239                         goto exit_bh;
 240                 }
 241                 if ((err = ext3_journal_get_write_access(handle, gdb))) {
 242                         brelse(gdb);
 243                         goto exit_bh;
 244                 }
 245                 lock_buffer(gdb);
 246                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
 247                 set_buffer_uptodate(gdb);
 248                 unlock_buffer(gdb);
 249                 err = ext3_journal_dirty_metadata(handle, gdb);
 250                 if (err) {
 251                         brelse(gdb);
 252                         goto exit_bh;
 253                 }
 254                 ext3_set_bit(bit, bh->b_data);
 255                 brelse(gdb);
 256         }
 257
 258         /* Zero out all of the reserved backup group descriptor table blocks */
 259         for (i = 0, bit = gdblocks + 1, block = start + bit;
 260              i < reserved_gdb; i++, block++, bit++) {
 261                 struct buffer_head *gdb;
 262
 263                 ext3_debug("clear reserved block %#04lx (+%d)\n", block, bit);
 264
 265                 err = extend_or_restart_transaction(handle, 1, bh);
 266                 if (err)
 267                         goto exit_bh;
 268
 269                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 270                         err = PTR_ERR(gdb);
 271                         goto exit_bh;
 272                 }
 273                 err = ext3_journal_dirty_metadata(handle, gdb);
 274                 if (err) {
 275                         brelse(gdb);
 276                         goto exit_bh;
 277                 }
 278                 ext3_set_bit(bit, bh->b_data);
 279                 brelse(gdb);
 280         }
 281         ext3_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
 282                    input->block_bitmap - start);
 283         ext3_set_bit(input->block_bitmap - start, bh->b_data);
 284         ext3_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
 285                    input->inode_bitmap - start);
 286         ext3_set_bit(input->inode_bitmap - start, bh->b_data);
 287
 288         /* Zero out all of the inode table blocks */
 289         for (i = 0, block = input->inode_table, bit = block - start;
 290              i < sbi->s_itb_per_group; i++, bit++, block++) {
 291                 struct buffer_head *it;
 292
 293                 ext3_debug("clear inode block %#04lx (+%d)\n", block, bit);
 294
 295                 err = extend_or_restart_transaction(handle, 1, bh);
 296                 if (err)
 297                         goto exit_bh;
 298
 299                 if (IS_ERR(it = bclean(handle, sb, block))) {
 300                         err = PTR_ERR(it);
 301                         goto exit_bh;
 302                 }
 303                 err = ext3_journal_dirty_metadata(handle, it);
 304                 if (err) {
 305                         brelse(it);
 306                         goto exit_bh;
 307                 }
 308                 brelse(it);
 309                 ext3_set_bit(bit, bh->b_data);
 310         }
 311
 312         err = extend_or_restart_transaction(handle, 2, bh);
 313         if (err)
 314                 goto exit_bh;
 315
 316         mark_bitmap_end(input->blocks_count, EXT3_BLOCKS_PER_GROUP(sb),
 317                         bh->b_data);
 318         err = ext3_journal_dirty_metadata(handle, bh);
 319         if (err)
 320                 goto exit_bh;
 321         brelse(bh);
 322
 323         /* Mark unused entries in inode bitmap used */
 324         ext3_debug("clear inode bitmap %#04x (+%ld)\n",
 325                    input->inode_bitmap, input->inode_bitmap - start);
 326         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 327                 err = PTR_ERR(bh);
 328                 goto exit_journal;
 329         }
 330
 331         mark_bitmap_end(EXT3_INODES_PER_GROUP(sb), EXT3_BLOCKS_PER_GROUP(sb),
 332                         bh->b_data);
 333         err = ext3_journal_dirty_metadata(handle, bh);
 334 exit_bh:
 335         brelse(bh);
 336
 337 exit_journal:
 338         mutex_unlock(&sbi->s_resize_lock);
 339         if ((err2 = ext3_journal_stop(handle)) && !err)
 340                 err = err2;
 341
 342         return err;
 343 }
 344
 345 /*
 346  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 347  * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
 348  * calling this for the first time.  In a sparse filesystem it will be the
 349  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 350  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 351  */
 352 static unsigned ext3_list_backups(struct super_block *sb, unsigned *three,
 353                                   unsigned *five, unsigned *seven)
 354 {
 355         unsigned *min = three;
 356         int mult = 3;
 357         unsigned ret;
 358
 359         if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
 360                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 361                 ret = *min;
 362                 *min += 1;
 363                 return ret;
 364         }
 365
 366         if (*five < *min) {
 367                 min = five;
 368                 mult = 5;
 369         }
 370         if (*seven < *min) {
 371                 min = seven;
 372                 mult = 7;
 373         }
 374
 375         ret = *min;
 376         *min *= mult;
 377
 378         return ret;
 379 }
 380
 381 /*
 382  * Check that all of the backup GDT blocks are held in the primary GDT block.
 383  * It is assumed that they are stored in group order.  Returns the number of
 384  * groups in current filesystem that have BACKUPS, or -ve error code.
 385  */
 386 static int verify_reserved_gdb(struct super_block *sb,
 387                                struct buffer_head *primary)
 388 {
 389         const ext3_fsblk_t blk = primary->b_blocknr;
 390         const unsigned long end = EXT3_SB(sb)->s_groups_count;
 391         unsigned three = 1;
 392         unsigned five = 5;
 393         unsigned seven = 7;
 394         unsigned grp;
 395         __le32 *p = (__le32 *)primary->b_data;
 396         int gdbackups = 0;
 397
 398         while ((grp = ext3_list_backups(sb, &three, &five, &seven)) < end) {
 399                 if (le32_to_cpu(*p++) != grp * EXT3_BLOCKS_PER_GROUP(sb) + blk){
 400                         ext3_warning(sb, __func__,
 401                                      "reserved GDT "E3FSBLK
 402                                      " missing grp %d ("E3FSBLK")",
 403                                      blk, grp,
 404                                      grp * EXT3_BLOCKS_PER_GROUP(sb) + blk);
 405                         return -EINVAL;
 406                 }
 407                 if (++gdbackups > EXT3_ADDR_PER_BLOCK(sb))
 408                         return -EFBIG;
 409         }
 410
 411         return gdbackups;
 412 }
 413
 414 /*
 415  * Called when we need to bring a reserved group descriptor table block into
 416  * use from the resize inode.  The primary copy of the new GDT block currently
 417  * is an indirect block (under the double indirect block in the resize inode).
 418  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 419  * block, in group order.  Even though we know all the block numbers we need,
 420  * we check to ensure that the resize inode has actually reserved these blocks.
 421  *
 422  * Don't need to update the block bitmaps because the blocks are still in use.
 423  *
 424  * We get all of the error cases out of the way, so that we are sure to not
 425  * fail once we start modifying the data on disk, because JBD has no rollback.
 426  */
 427 static int add_new_gdb(handle_t *handle, struct inode *inode,
 428                        struct ext3_new_group_data *input,
 429                        struct buffer_head **primary)
 430 {
 431         struct super_block *sb = inode->i_sb;
 432         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
 433         unsigned long gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 434         ext3_fsblk_t gdblock = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 435         struct buffer_head **o_group_desc, **n_group_desc;
 436         struct buffer_head *dind;
 437         int gdbackups;
 438         struct ext3_iloc iloc;
 439         __le32 *data;
 440         int err;
 441
 442         if (test_opt(sb, DEBUG))
 443                 printk(KERN_DEBUG
 444                        "EXT3-fs: ext3_add_new_gdb: adding group block %lu\n",
 445                        gdb_num);
 446
 447         /*
 448          * If we are not using the primary superblock/GDT copy don't resize,
 449          * because the user tools have no way of handling this.  Probably a
 450          * bad time to do it anyways.
 451          */
 452         if (EXT3_SB(sb)->s_sbh->b_blocknr !=
 453             le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) {
 454                 ext3_warning(sb, __func__,
 455                         "won't resize using backup superblock at %llu",
 456                         (unsigned long long)EXT3_SB(sb)->s_sbh->b_blocknr);
 457                 return -EPERM;
 458         }
 459
 460         *primary = sb_bread(sb, gdblock);
 461         if (!*primary)
 462                 return -EIO;
 463
 464         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 465                 err = gdbackups;
 466                 goto exit_bh;
 467         }
 468
 469         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 470         dind = sb_bread(sb, le32_to_cpu(*data));
 471         if (!dind) {
 472                 err = -EIO;
 473                 goto exit_bh;
 474         }
 475
 476         data = (__le32 *)dind->b_data;
 477         if (le32_to_cpu(data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)]) != gdblock) {
 478                 ext3_warning(sb, __func__,
 479                              "new group %u GDT block "E3FSBLK" not reserved",
 480                              input->group, gdblock);
 481                 err = -EINVAL;
 482                 goto exit_dind;
 483         }
 484
 485         if ((err = ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh)))
 486                 goto exit_dind;
 487
 488         if ((err = ext3_journal_get_write_access(handle, *primary)))
 489                 goto exit_sbh;
 490
 491         if ((err = ext3_journal_get_write_access(handle, dind)))
 492                 goto exit_primary;
 493
 494         /* ext3_reserve_inode_write() gets a reference on the iloc */
 495         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 496                 goto exit_dindj;
 497
 498         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 499                         GFP_NOFS);
 500         if (!n_group_desc) {
 501                 err = -ENOMEM;
 502                 ext3_warning (sb, __func__,
 503                               "not enough memory for %lu groups", gdb_num + 1);
 504                 goto exit_inode;
 505         }
 506
 507         /*
 508          * Finally, we have all of the possible failures behind us...
 509          *
 510          * Remove new GDT block from inode double-indirect block and clear out
 511          * the new GDT block for use (which also "frees" the backup GDT blocks
 512          * from the reserved inode).  We don't need to change the bitmaps for
 513          * these blocks, because they are marked as in-use from being in the
 514          * reserved inode, and will become GDT blocks (primary and backup).
 515          */
 516         data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)] = 0;
 517         err = ext3_journal_dirty_metadata(handle, dind);
 518         if (err)
 519                 goto exit_group_desc;
 520         brelse(dind);
 521         dind = NULL;
 522         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 523         err = ext3_mark_iloc_dirty(handle, inode, &iloc);
 524         if (err)
 525                 goto exit_group_desc;
 526         memset((*primary)->b_data, 0, sb->s_blocksize);
 527         err = ext3_journal_dirty_metadata(handle, *primary);
 528         if (err)
 529                 goto exit_group_desc;
 530
 531         o_group_desc = EXT3_SB(sb)->s_group_desc;
 532         memcpy(n_group_desc, o_group_desc,
 533                EXT3_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 534         n_group_desc[gdb_num] = *primary;
 535         EXT3_SB(sb)->s_group_desc = n_group_desc;
 536         EXT3_SB(sb)->s_gdb_count++;
 537         kfree(o_group_desc);
 538
 539         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 540         err = ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 541         if (err)
 542                 goto exit_inode;
 543
 544         return 0;
 545
 546 exit_group_desc:
 547         kfree(n_group_desc);
 548 exit_inode:
 549         //ext3_journal_release_buffer(handle, iloc.bh);
 550         brelse(iloc.bh);
 551 exit_dindj:
 552         //ext3_journal_release_buffer(handle, dind);
 553 exit_primary:
 554         //ext3_journal_release_buffer(handle, *primary);
 555 exit_sbh:
 556         //ext3_journal_release_buffer(handle, *primary);
 557 exit_dind:
 558         brelse(dind);
 559 exit_bh:
 560         brelse(*primary);
 561
 562         ext3_debug("leaving with error %d\n", err);
 563         return err;
 564 }
 565
 566 /*
 567  * Called when we are adding a new group which has a backup copy of each of
 568  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 569  * We need to add these reserved backup GDT blocks to the resize inode, so
 570  * that they are kept for future resizing and not allocated to files.
 571  *
 572  * Each reserved backup GDT block will go into a different indirect block.
 573  * The indirect blocks are actually the primary reserved GDT blocks,
 574  * so we know in advance what their block numbers are.  We only get the
 575  * double-indirect block to verify it is pointing to the primary reserved
 576  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 577  * backup GDT blocks are stored in their reserved primary GDT block.
 578  */
 579 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 580                               struct ext3_new_group_data *input)
 581 {
 582         struct super_block *sb = inode->i_sb;
 583         int reserved_gdb =le16_to_cpu(EXT3_SB(sb)->s_es->s_reserved_gdt_blocks);
 584         struct buffer_head **primary;
 585         struct buffer_head *dind;
 586         struct ext3_iloc iloc;
 587         ext3_fsblk_t blk;
 588         __le32 *data, *end;
 589         int gdbackups = 0;
 590         int res, i;
 591         int err;
 592
 593         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 594         if (!primary)
 595                 return -ENOMEM;
 596
 597         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 598         dind = sb_bread(sb, le32_to_cpu(*data));
 599         if (!dind) {
 600                 err = -EIO;
 601                 goto exit_free;
 602         }
 603
 604         blk = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + EXT3_SB(sb)->s_gdb_count;
 605         data = (__le32 *)dind->b_data + (EXT3_SB(sb)->s_gdb_count %
 606                                          EXT3_ADDR_PER_BLOCK(sb));
 607         end = (__le32 *)dind->b_data + EXT3_ADDR_PER_BLOCK(sb);
 608
 609         /* Get each reserved primary GDT block and verify it holds backups */
 610         for (res = 0; res < reserved_gdb; res++, blk++) {
 611                 if (le32_to_cpu(*data) != blk) {
 612                         ext3_warning(sb, __func__,
 613                                      "reserved block "E3FSBLK
 614                                      " not at offset %ld",
 615                                      blk,
 616                                      (long)(data - (__le32 *)dind->b_data));
 617                         err = -EINVAL;
 618                         goto exit_bh;
 619                 }
 620                 primary[res] = sb_bread(sb, blk);
 621                 if (!primary[res]) {
 622                         err = -EIO;
 623                         goto exit_bh;
 624                 }
 625                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 626                         brelse(primary[res]);
 627                         err = gdbackups;
 628                         goto exit_bh;
 629                 }
 630                 if (++data >= end)
 631                         data = (__le32 *)dind->b_data;
 632         }
 633
 634         for (i = 0; i < reserved_gdb; i++) {
 635                 if ((err = ext3_journal_get_write_access(handle, primary[i]))) {
 636                         /*
 637                         int j;
 638                         for (j = 0; j < i; j++)
 639                                 ext3_journal_release_buffer(handle, primary[j]);
 640                          */
 641                         goto exit_bh;
 642                 }
 643         }
 644
 645         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 646                 goto exit_bh;
 647
 648         /*
 649          * Finally we can add each of the reserved backup GDT blocks from
 650          * the new group to its reserved primary GDT block.
 651          */
 652         blk = input->group * EXT3_BLOCKS_PER_GROUP(sb);
 653         for (i = 0; i < reserved_gdb; i++) {
 654                 int err2;
 655                 data = (__le32 *)primary[i]->b_data;
 656                 /* printk("reserving backup %lu[%u] = %lu\n",
 657                        primary[i]->b_blocknr, gdbackups,
 658                        blk + primary[i]->b_blocknr); */
 659                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 660                 err2 = ext3_journal_dirty_metadata(handle, primary[i]);
 661                 if (!err)
 662                         err = err2;
 663         }
 664         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 665         ext3_mark_iloc_dirty(handle, inode, &iloc);
 666
 667 exit_bh:
 668         while (--res >= 0)
 669                 brelse(primary[res]);
 670         brelse(dind);
 671
 672 exit_free:
 673         kfree(primary);
 674
 675         return err;
 676 }
 677
 678 /*
 679  * Update the backup copies of the ext3 metadata.  These don't need to be part
 680  * of the main resize transaction, because e2fsck will re-write them if there
 681  * is a problem (basically only OOM will cause a problem).  However, we
 682  * _should_ update the backups if possible, in case the primary gets trashed
 683  * for some reason and we need to run e2fsck from a backup superblock.  The
 684  * important part is that the new block and inode counts are in the backup
 685  * superblocks, and the location of the new group metadata in the GDT backups.
 686  *
 687  * We do not need take the s_resize_lock for this, because these
 688  * blocks are not otherwise touched by the filesystem code when it is
 689  * mounted.  We don't need to worry about last changing from
 690  * sbi->s_groups_count, because the worst that can happen is that we
 691  * do not copy the full number of backups at this time.  The resize
 692  * which changed s_groups_count will backup again.
 693  */
 694 static void update_backups(struct super_block *sb,
 695                            int blk_off, char *data, int size)
 696 {
 697         struct ext3_sb_info *sbi = EXT3_SB(sb);
 698         const unsigned long last = sbi->s_groups_count;
 699         const int bpg = EXT3_BLOCKS_PER_GROUP(sb);
 700         unsigned three = 1;
 701         unsigned five = 5;
 702         unsigned seven = 7;
 703         unsigned group;
 704         int rest = sb->s_blocksize - size;
 705         handle_t *handle;
 706         int err = 0, err2;
 707
 708         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 709         if (IS_ERR(handle)) {
 710                 group = 1;
 711                 err = PTR_ERR(handle);
 712                 goto exit_err;
 713         }
 714
 715         while ((group = ext3_list_backups(sb, &three, &five, &seven)) < last) {
 716                 struct buffer_head *bh;
 717
 718                 /* Out of journal space, and can't get more - abort - so sad */
 719                 if (handle->h_buffer_credits == 0 &&
 720                     ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA) &&
 721                     (err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA)))
 722                         break;
 723
 724                 bh = sb_getblk(sb, group * bpg + blk_off);
 725                 if (unlikely(!bh)) {
 726                         err = -ENOMEM;
 727                         break;
 728                 }
 729                 ext3_debug("update metadata backup %#04lx\n",
 730                           (unsigned long)bh->b_blocknr);
 731                 if ((err = ext3_journal_get_write_access(handle, bh))) {
 732                         brelse(bh);
 733                         break;
 734                 }
 735                 lock_buffer(bh);
 736                 memcpy(bh->b_data, data, size);
 737                 if (rest)
 738                         memset(bh->b_data + size, 0, rest);
 739                 set_buffer_uptodate(bh);
 740                 unlock_buffer(bh);
 741                 err = ext3_journal_dirty_metadata(handle, bh);
 742                 brelse(bh);
 743                 if (err)
 744                         break;
 745         }
 746         if ((err2 = ext3_journal_stop(handle)) && !err)
 747                 err = err2;
 748
 749         /*
 750          * Ugh! Need to have e2fsck write the backup copies.  It is too
 751          * late to revert the resize, we shouldn't fail just because of
 752          * the backup copies (they are only needed in case of corruption).
 753          *
 754          * However, if we got here we have a journal problem too, so we
 755          * can't really start a transaction to mark the superblock.
 756          * Chicken out and just set the flag on the hope it will be written
 757          * to disk, and if not - we will simply wait until next fsck.
 758          */
 759 exit_err:
 760         if (err) {
 761                 ext3_warning(sb, __func__,
 762                              "can't update backup for group %d (err %d), "
 763                              "forcing fsck on next reboot", group, err);
 764                 sbi->s_mount_state &= ~EXT3_VALID_FS;
 765                 sbi->s_es->s_state &= cpu_to_le16(~EXT3_VALID_FS);
 766                 mark_buffer_dirty(sbi->s_sbh);
 767         }
 768 }
 769
 770 /* Add group descriptor data to an existing or new group descriptor block.
 771  * Ensure we handle all possible error conditions _before_ we start modifying
 772  * the filesystem, because we cannot abort the transaction and not have it
 773  * write the data to disk.
 774  *
 775  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 776  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 777  *
 778  * We only need to hold the superblock lock while we are actually adding
 779  * in the new group's counts to the superblock.  Prior to that we have
 780  * not really "added" the group at all.  We re-check that we are still
 781  * adding in the last group in case things have changed since verifying.
 782  */
 783 int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input)
 784 {
 785         struct ext3_sb_info *sbi = EXT3_SB(sb);
 786         struct ext3_super_block *es = sbi->s_es;
 787         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 788                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 789         struct buffer_head *primary = NULL;
 790         struct ext3_group_desc *gdp;
 791         struct inode *inode = NULL;
 792         handle_t *handle;
 793         int gdb_off, gdb_num;
 794         int err, err2;
 795
 796         gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 797         gdb_off = input->group % EXT3_DESC_PER_BLOCK(sb);
 798
 799         if (gdb_off == 0 && !EXT3_HAS_RO_COMPAT_FEATURE(sb,
 800                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 801                 ext3_warning(sb, __func__,
 802                              "Can't resize non-sparse filesystem further");
 803                 return -EPERM;
 804         }
 805
 806         if (le32_to_cpu(es->s_blocks_count) + input->blocks_count <
 807             le32_to_cpu(es->s_blocks_count)) {
 808                 ext3_warning(sb, __func__, "blocks_count overflow\n");
 809                 return -EINVAL;
 810         }
 811
 812         if (le32_to_cpu(es->s_inodes_count) + EXT3_INODES_PER_GROUP(sb) <
 813             le32_to_cpu(es->s_inodes_count)) {
 814                 ext3_warning(sb, __func__, "inodes_count overflow\n");
 815                 return -EINVAL;
 816         }
 817
 818         if (reserved_gdb || gdb_off == 0) {
 819                 if (!EXT3_HAS_COMPAT_FEATURE(sb,
 820                                              EXT3_FEATURE_COMPAT_RESIZE_INODE)
 821                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
 822                         ext3_warning(sb, __func__,
 823                                      "No reserved GDT blocks, can't resize");
 824                         return -EPERM;
 825                 }
 826                 inode = ext3_iget(sb, EXT3_RESIZE_INO);
 827                 if (IS_ERR(inode)) {
 828                         ext3_warning(sb, __func__,
 829                                      "Error opening resize inode");
 830                         return PTR_ERR(inode);
 831                 }
 832         }
 833
 834         if ((err = verify_group_input(sb, input)))
 835                 goto exit_put;
 836
 837         if ((err = setup_new_group_blocks(sb, input)))
 838                 goto exit_put;
 839
 840         /*
 841          * We will always be modifying at least the superblock and a GDT
 842          * block.  If we are adding a group past the last current GDT block,
 843          * we will also modify the inode and the dindirect block.  If we
 844          * are adding a group with superblock/GDT backups  we will also
 845          * modify each of the reserved GDT dindirect blocks.
 846          */
 847         handle = ext3_journal_start_sb(sb,
 848                                        ext3_bg_has_super(sb, input->group) ?
 849                                        3 + reserved_gdb : 4);
 850         if (IS_ERR(handle)) {
 851                 err = PTR_ERR(handle);
 852                 goto exit_put;
 853         }
 854
 855         mutex_lock(&sbi->s_resize_lock);
 856         if (input->group != sbi->s_groups_count) {
 857                 ext3_warning(sb, __func__,
 858                              "multiple resizers run on filesystem!");
 859                 err = -EBUSY;
 860                 goto exit_journal;
 861         }
 862
 863         if ((err = ext3_journal_get_write_access(handle, sbi->s_sbh)))
 864                 goto exit_journal;
 865
 866         /*
 867          * We will only either add reserved group blocks to a backup group
 868          * or remove reserved blocks for the first group in a new group block.
 869          * Doing both would be mean more complex code, and sane people don't
 870          * use non-sparse filesystems anymore.  This is already checked above.
 871          */
 872         if (gdb_off) {
 873                 primary = sbi->s_group_desc[gdb_num];
 874                 if ((err = ext3_journal_get_write_access(handle, primary)))
 875                         goto exit_journal;
 876
 877                 if (reserved_gdb && ext3_bg_num_gdb(sb, input->group) &&
 878                     (err = reserve_backup_gdb(handle, inode, input)))
 879                         goto exit_journal;
 880         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 881                 goto exit_journal;
 882
 883         /*
 884          * OK, now we've set up the new group.  Time to make it active.
 885          *
 886          * We do not lock all allocations via s_resize_lock
 887          * so we have to be safe wrt. concurrent accesses the group
 888          * data.  So we need to be careful to set all of the relevant
 889          * group descriptor data etc. *before* we enable the group.
 890          *
 891          * The key field here is sbi->s_groups_count: as long as
 892          * that retains its old value, nobody is going to access the new
 893          * group.
 894          *
 895          * So first we update all the descriptor metadata for the new
 896          * group; then we update the total disk blocks count; then we
 897          * update the groups count to enable the group; then finally we
 898          * update the free space counts so that the system can start
 899          * using the new disk blocks.
 900          */
 901
 902         /* Update group descriptor block for new group */
 903         gdp = (struct ext3_group_desc *)primary->b_data + gdb_off;
 904
 905         gdp->bg_block_bitmap = cpu_to_le32(input->block_bitmap);
 906         gdp->bg_inode_bitmap = cpu_to_le32(input->inode_bitmap);
 907         gdp->bg_inode_table = cpu_to_le32(input->inode_table);
 908         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 909         gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
 910
 911         /*
 912          * Make the new blocks and inodes valid next.  We do this before
 913          * increasing the group count so that once the group is enabled,
 914          * all of its blocks and inodes are already valid.
 915          *
 916          * We always allocate group-by-group, then block-by-block or
 917          * inode-by-inode within a group, so enabling these
 918          * blocks/inodes before the group is live won't actually let us
 919          * allocate the new space yet.
 920          */
 921         le32_add_cpu(&es->s_blocks_count, input->blocks_count);
 922         le32_add_cpu(&es->s_inodes_count, EXT3_INODES_PER_GROUP(sb));
 923
 924         /*
 925          * We need to protect s_groups_count against other CPUs seeing
 926          * inconsistent state in the superblock.
 927          *
 928          * The precise rules we use are:
 929          *
 930          * * Writers of s_groups_count *must* hold s_resize_lock
 931          * AND
 932          * * Writers must perform a smp_wmb() after updating all dependent
 933          *   data and before modifying the groups count
 934          *
 935          * * Readers must hold s_resize_lock over the access
 936          * OR
 937          * * Readers must perform an smp_rmb() after reading the groups count
 938          *   and before reading any dependent data.
 939          *
 940          * NB. These rules can be relaxed when checking the group count
 941          * while freeing data, as we can only allocate from a block
 942          * group after serialising against the group count, and we can
 943          * only then free after serialising in turn against that
 944          * allocation.
 945          */
 946         smp_wmb();
 947
 948         /* Update the global fs size fields */
 949         sbi->s_groups_count++;
 950
 951         err = ext3_journal_dirty_metadata(handle, primary);
 952         if (err)
 953                 goto exit_journal;
 954
 955         /* Update the reserved block counts only once the new group is
 956          * active. */
 957         le32_add_cpu(&es->s_r_blocks_count, input->reserved_blocks);
 958
 959         /* Update the free space counts */
 960         percpu_counter_add(&sbi->s_freeblocks_counter,
 961                            input->free_blocks_count);
 962         percpu_counter_add(&sbi->s_freeinodes_counter,
 963                            EXT3_INODES_PER_GROUP(sb));
 964
 965         err = ext3_journal_dirty_metadata(handle, sbi->s_sbh);
 966
 967 exit_journal:
 968         mutex_unlock(&sbi->s_resize_lock);
 969         if ((err2 = ext3_journal_stop(handle)) && !err)
 970                 err = err2;
 971         if (!err) {
 972                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 973                                sizeof(struct ext3_super_block));
 974                 update_backups(sb, primary->b_blocknr, primary->b_data,
 975                                primary->b_size);
 976         }
 977 exit_put:
 978         iput(inode);
 979         return err;
 980 } /* ext3_group_add */
 981
 982 /* Extend the filesystem to the new number of blocks specified.  This entry
 983  * point is only used to extend the current filesystem to the end of the last
 984  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 985  * for emergencies (because it has no dependencies on reserved blocks).
 986  *
 987  * If we _really_ wanted, we could use default values to call ext3_group_add()
 988  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 989  * GDT blocks are reserved to grow to the desired size.
 990  */
 991 int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es,
 992                       ext3_fsblk_t n_blocks_count)
 993 {
 994         ext3_fsblk_t o_blocks_count;
 995         ext3_grpblk_t last;
 996         ext3_grpblk_t add;
 997         struct buffer_head * bh;
 998         handle_t *handle;
 999         int err;
1000         unsigned long freed_blocks;
1001
1002         /* We don't need to worry about locking wrt other resizers just
1003          * yet: we're going to revalidate es->s_blocks_count after
1004          * taking the s_resize_lock below. */
1005         o_blocks_count = le32_to_cpu(es->s_blocks_count);
1006
1007         if (test_opt(sb, DEBUG))
1008                 printk(KERN_DEBUG "EXT3-fs: extending last group from "E3FSBLK
1009                        " up to "E3FSBLK" blocks\n",
1010                        o_blocks_count, n_blocks_count);
1011
1012         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1013                 return 0;
1014
1015         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1016                 printk(KERN_ERR "EXT3-fs: filesystem on %s:"
1017                         " too large to resize to "E3FSBLK" blocks safely\n",
1018                         sb->s_id, n_blocks_count);
1019                 if (sizeof(sector_t) < 8)
1020                         ext3_warning(sb, __func__,
1021                         "CONFIG_LBDAF not enabled\n");
1022                 return -EINVAL;
1023         }
1024
1025         if (n_blocks_count < o_blocks_count) {
1026                 ext3_warning(sb, __func__,
1027                              "can't shrink FS - resize aborted");
1028                 return -EBUSY;
1029         }
1030
1031         /* Handle the remaining blocks in the last group only. */
1032         last = (o_blocks_count - le32_to_cpu(es->s_first_data_block)) %
1033                 EXT3_BLOCKS_PER_GROUP(sb);
1034
1035         if (last == 0) {
1036                 ext3_warning(sb, __func__,
1037                              "need to use ext2online to resize further");
1038                 return -EPERM;
1039         }
1040
1041         add = EXT3_BLOCKS_PER_GROUP(sb) - last;
1042
1043         if (o_blocks_count + add < o_blocks_count) {
1044                 ext3_warning(sb, __func__, "blocks_count overflow");
1045                 return -EINVAL;
1046         }
1047
1048         if (o_blocks_count + add > n_blocks_count)
1049                 add = n_blocks_count - o_blocks_count;
1050
1051         if (o_blocks_count + add < n_blocks_count)
1052                 ext3_warning(sb, __func__,
1053                              "will only finish group ("E3FSBLK
1054                              " blocks, %u new)",
1055                              o_blocks_count + add, add);
1056
1057         /* See if the device is actually as big as what was requested */
1058         bh = sb_bread(sb, o_blocks_count + add -1);
1059         if (!bh) {
1060                 ext3_warning(sb, __func__,
1061                              "can't read last block, resize aborted");
1062                 return -ENOSPC;
1063         }
1064         brelse(bh);
1065
1066         /* We will update the superblock, one block bitmap, and
1067          * one group descriptor via ext3_free_blocks().
1068          */
1069         handle = ext3_journal_start_sb(sb, 3);
1070         if (IS_ERR(handle)) {
1071                 err = PTR_ERR(handle);
1072                 ext3_warning(sb, __func__, "error %d on journal start",err);
1073                 goto exit_put;
1074         }
1075
1076         mutex_lock(&EXT3_SB(sb)->s_resize_lock);
1077         if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
1078                 ext3_warning(sb, __func__,
1079                              "multiple resizers run on filesystem!");
1080                 mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1081                 ext3_journal_stop(handle);
1082                 err = -EBUSY;
1083                 goto exit_put;
1084         }
1085
1086         if ((err = ext3_journal_get_write_access(handle,
1087                                                  EXT3_SB(sb)->s_sbh))) {
1088                 ext3_warning(sb, __func__,
1089                              "error %d on journal write access", err);
1090                 mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1091                 ext3_journal_stop(handle);
1092                 goto exit_put;
1093         }
1094         es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
1095         err = ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
1096         mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1097         if (err) {
1098                 ext3_warning(sb, __func__,
1099                              "error %d on journal dirty metadata", err);
1100                 ext3_journal_stop(handle);
1101                 goto exit_put;
1102         }
1103         ext3_debug("freeing blocks "E3FSBLK" through "E3FSBLK"\n",
1104                    o_blocks_count, o_blocks_count + add);
1105         ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1106         ext3_debug("freed blocks "E3FSBLK" through "E3FSBLK"\n",
1107                    o_blocks_count, o_blocks_count + add);
1108         if ((err = ext3_journal_stop(handle)))
1109                 goto exit_put;
1110         if (test_opt(sb, DEBUG))
1111                 printk(KERN_DEBUG "EXT3-fs: extended group to %u blocks\n",
1112                        le32_to_cpu(es->s_blocks_count));
1113         update_backups(sb, EXT3_SB(sb)->s_sbh->b_blocknr, (char *)es,
1114                        sizeof(struct ext3_super_block));
1115 exit_put:
1116         return err;
1117 } /* ext3_group_extend */