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 <linux/ext3_jbd.h>
  15
  16 #include <linux/errno.h>
  17 #include <linux/slab.h>
  18
  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 ext3_new_group_data *input)
  25 {
  26         struct ext3_sb_info *sbi = EXT3_SB(sb);
  27         struct ext3_super_block *es = sbi->s_es;
  28         ext3_fsblk_t start = le32_to_cpu(es->s_blocks_count);
  29         ext3_fsblk_t end = start + input->blocks_count;
  30         unsigned group = input->group;
  31         ext3_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  32         unsigned overhead = ext3_bg_has_super(sb, group) ?
  33                 (1 + ext3_bg_num_gdb(sb, group) +
  34                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  35         ext3_fsblk_t metaend = start + overhead;
  36         struct buffer_head *bh = NULL;
  37         ext3_grpblk_t free_blocks_count;
  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 "EXT3-fs: adding %s group %u: %u blocks "
  45                        "(%d free, %u reserved)\n",
  46                        ext3_bg_has_super(sb, input->group) ? "normal" :
  47                        "no-super", input->group, input->blocks_count,
  48                        free_blocks_count, input->reserved_blocks);
  49
  50         if (group != sbi->s_groups_count)
  51                 ext3_warning(sb, __func__,
  52                              "Cannot add at group %u (only %lu groups)",
  53                              input->group, sbi->s_groups_count);
  54         else if ((start - le32_to_cpu(es->s_first_data_block)) %
  55                  EXT3_BLOCKS_PER_GROUP(sb))
  56                 ext3_warning(sb, __func__, "Last group not full");
  57         else if (input->reserved_blocks > input->blocks_count / 5)
  58                 ext3_warning(sb, __func__, "Reserved blocks too high (%u)",
  59                              input->reserved_blocks);
  60         else if (free_blocks_count < 0)
  61                 ext3_warning(sb, __func__, "Bad blocks count %u",
  62                              input->blocks_count);
  63         else if (!(bh = sb_bread(sb, end - 1)))
  64                 ext3_warning(sb, __func__,
  65                              "Cannot read last block ("E3FSBLK")",
  66                              end - 1);
  67         else if (outside(input->block_bitmap, start, end))
  68                 ext3_warning(sb, __func__,
  69                              "Block bitmap not in group (block %u)",
  70                              input->block_bitmap);
  71         else if (outside(input->inode_bitmap, start, end))
  72                 ext3_warning(sb, __func__,
  73                              "Inode bitmap not in group (block %u)",
  74                              input->inode_bitmap);
  75         else if (outside(input->inode_table, start, end) ||
  76                  outside(itend - 1, start, end))
  77                 ext3_warning(sb, __func__,
  78                              "Inode table not in group (blocks %u-"E3FSBLK")",
  79                              input->inode_table, itend - 1);
  80         else if (input->inode_bitmap == input->block_bitmap)
  81                 ext3_warning(sb, __func__,
  82                              "Block bitmap same as inode bitmap (%u)",
  83                              input->block_bitmap);
  84         else if (inside(input->block_bitmap, input->inode_table, itend))
  85                 ext3_warning(sb, __func__,
  86                              "Block bitmap (%u) in inode table (%u-"E3FSBLK")",
  87                              input->block_bitmap, input->inode_table, itend-1);
  88         else if (inside(input->inode_bitmap, input->inode_table, itend))
  89                 ext3_warning(sb, __func__,
  90                              "Inode bitmap (%u) in inode table (%u-"E3FSBLK")",
  91                              input->inode_bitmap, input->inode_table, itend-1);
  92         else if (inside(input->block_bitmap, start, metaend))
  93                 ext3_warning(sb, __func__,
  94                              "Block bitmap (%u) in GDT table"
  95                              " ("E3FSBLK"-"E3FSBLK")",
  96                              input->block_bitmap, start, metaend - 1);
  97         else if (inside(input->inode_bitmap, start, metaend))
  98                 ext3_warning(sb, __func__,
  99                              "Inode bitmap (%u) in GDT table"
 100                              " ("E3FSBLK"-"E3FSBLK")",
 101                              input->inode_bitmap, start, metaend - 1);
 102         else if (inside(input->inode_table, start, metaend) ||
 103                  inside(itend - 1, start, metaend))
 104                 ext3_warning(sb, __func__,
 105                              "Inode table (%u-"E3FSBLK") overlaps"
 106                              "GDT table ("E3FSBLK"-"E3FSBLK")",
 107                              input->inode_table, itend - 1, start, metaend - 1);
 108         else
 109                 err = 0;
 110         brelse(bh);
 111
 112         return err;
 113 }
 114
 115 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 116                                   ext3_fsblk_t blk)
 117 {
 118         struct buffer_head *bh;
 119         int err;
 120
 121         bh = sb_getblk(sb, blk);
 122         if (!bh)
 123                 return ERR_PTR(-EIO);
 124         if ((err = ext3_journal_get_write_access(handle, bh))) {
 125                 brelse(bh);
 126                 bh = ERR_PTR(err);
 127         } else {
 128                 lock_buffer(bh);
 129                 memset(bh->b_data, 0, sb->s_blocksize);
 130                 set_buffer_uptodate(bh);
 131                 unlock_buffer(bh);
 132         }
 133
 134         return bh;
 135 }
 136
 137 /*
 138  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 139  * need to use it within a single byte (to ensure we get endianness right).
 140  * We can use memset for the rest of the bitmap as there are no other users.
 141  */
 142 static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 143 {
 144         int i;
 145
 146         if (start_bit >= end_bit)
 147                 return;
 148
 149         ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 150         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 151                 ext3_set_bit(i, bitmap);
 152         if (i < end_bit)
 153                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 154 }
 155
 156 /*
 157  * If we have fewer than thresh credits, extend by EXT3_MAX_TRANS_DATA.
 158  * If that fails, restart the transaction & regain write access for the
 159  * buffer head which is used for block_bitmap modifications.
 160  */
 161 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 162                                          struct buffer_head *bh)
 163 {
 164         int err;
 165
 166         if (handle->h_buffer_credits >= thresh)
 167                 return 0;
 168
 169         err = ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA);
 170         if (err < 0)
 171                 return err;
 172         if (err) {
 173                 err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA);
 174                 if (err)
 175                         return err;
 176                 err = ext3_journal_get_write_access(handle, bh);
 177                 if (err)
 178                         return err;
 179         }
 180
 181         return 0;
 182 }
 183
 184 /*
 185  * Set up the block and inode bitmaps, and the inode table for the new group.
 186  * This doesn't need to be part of the main transaction, since we are only
 187  * changing blocks outside the actual filesystem.  We still do journaling to
 188  * ensure the recovery is correct in case of a failure just after resize.
 189  * If any part of this fails, we simply abort the resize.
 190  */
 191 static int setup_new_group_blocks(struct super_block *sb,
 192                                   struct ext3_new_group_data *input)
 193 {
 194         struct ext3_sb_info *sbi = EXT3_SB(sb);
 195         ext3_fsblk_t start = ext3_group_first_block_no(sb, input->group);
 196         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 197                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 198         unsigned long gdblocks = ext3_bg_num_gdb(sb, input->group);
 199         struct buffer_head *bh;
 200         handle_t *handle;
 201         ext3_fsblk_t block;
 202         ext3_grpblk_t bit;
 203         int i;
 204         int err = 0, err2;
 205
 206         /* This transaction may be extended/restarted along the way */
 207         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 208
 209         if (IS_ERR(handle))
 210                 return PTR_ERR(handle);
 211
 212         mutex_lock(&sbi->s_resize_lock);
 213         if (input->group != sbi->s_groups_count) {
 214                 err = -EBUSY;
 215                 goto exit_journal;
 216         }
 217
 218         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 219                 err = PTR_ERR(bh);
 220                 goto exit_journal;
 221         }
 222
 223         if (ext3_bg_has_super(sb, input->group)) {
 224                 ext3_debug("mark backup superblock %#04lx (+0)\n", start);
 225                 ext3_set_bit(0, bh->b_data);
 226         }
 227
 228         /* Copy all of the GDT blocks into the backup in this group */
 229         for (i = 0, bit = 1, block = start + 1;
 230              i < gdblocks; i++, block++, bit++) {
 231                 struct buffer_head *gdb;
 232
 233                 ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
 234
 235                 err = extend_or_restart_transaction(handle, 1, bh);
 236                 if (err)
 237                         goto exit_bh;
 238
 239                 gdb = sb_getblk(sb, block);
 240                 if (!gdb) {
 241                         err = -EIO;
 242                         goto exit_bh;
 243                 }
 244                 if ((err = ext3_journal_get_write_access(handle, gdb))) {
 245                         brelse(gdb);
 246                         goto exit_bh;
 247                 }
 248                 lock_buffer(gdb);
 249                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
 250                 set_buffer_uptodate(gdb);
 251                 unlock_buffer(gdb);
 252                 ext3_journal_dirty_metadata(handle, gdb);
 253                 ext3_set_bit(bit, bh->b_data);
 254                 brelse(gdb);
 255         }
 256
 257         /* Zero out all of the reserved backup group descriptor table blocks */
 258         for (i = 0, bit = gdblocks + 1, block = start + bit;
 259              i < reserved_gdb; i++, block++, bit++) {
 260                 struct buffer_head *gdb;
 261
 262                 ext3_debug("clear reserved block %#04lx (+%d)\n", block, bit);
 263
 264                 err = extend_or_restart_transaction(handle, 1, bh);
 265                 if (err)
 266                         goto exit_bh;
 267
 268                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 269                         err = PTR_ERR(gdb);
 270                         goto exit_bh;
 271                 }
 272                 ext3_journal_dirty_metadata(handle, gdb);
 273                 ext3_set_bit(bit, bh->b_data);
 274                 brelse(gdb);
 275         }
 276         ext3_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
 277                    input->block_bitmap - start);
 278         ext3_set_bit(input->block_bitmap - start, bh->b_data);
 279         ext3_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
 280                    input->inode_bitmap - start);
 281         ext3_set_bit(input->inode_bitmap - start, bh->b_data);
 282
 283         /* Zero out all of the inode table blocks */
 284         for (i = 0, block = input->inode_table, bit = block - start;
 285              i < sbi->s_itb_per_group; i++, bit++, block++) {
 286                 struct buffer_head *it;
 287
 288                 ext3_debug("clear inode block %#04lx (+%d)\n", block, bit);
 289
 290                 err = extend_or_restart_transaction(handle, 1, bh);
 291                 if (err)
 292                         goto exit_bh;
 293
 294                 if (IS_ERR(it = bclean(handle, sb, block))) {
 295                         err = PTR_ERR(it);
 296                         goto exit_bh;
 297                 }
 298                 ext3_journal_dirty_metadata(handle, it);
 299                 brelse(it);
 300                 ext3_set_bit(bit, bh->b_data);
 301         }
 302
 303         err = extend_or_restart_transaction(handle, 2, bh);
 304         if (err)
 305                 goto exit_bh;
 306
 307         mark_bitmap_end(input->blocks_count, EXT3_BLOCKS_PER_GROUP(sb),
 308                         bh->b_data);
 309         ext3_journal_dirty_metadata(handle, bh);
 310         brelse(bh);
 311
 312         /* Mark unused entries in inode bitmap used */
 313         ext3_debug("clear inode bitmap %#04x (+%ld)\n",
 314                    input->inode_bitmap, input->inode_bitmap - start);
 315         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 316                 err = PTR_ERR(bh);
 317                 goto exit_journal;
 318         }
 319
 320         mark_bitmap_end(EXT3_INODES_PER_GROUP(sb), EXT3_BLOCKS_PER_GROUP(sb),
 321                         bh->b_data);
 322         ext3_journal_dirty_metadata(handle, bh);
 323 exit_bh:
 324         brelse(bh);
 325
 326 exit_journal:
 327         mutex_unlock(&sbi->s_resize_lock);
 328         if ((err2 = ext3_journal_stop(handle)) && !err)
 329                 err = err2;
 330
 331         return err;
 332 }
 333
 334 /*
 335  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 336  * ext3 filesystem.  The counters should be initialized to 1, 5, and 7 before
 337  * calling this for the first time.  In a sparse filesystem it will be the
 338  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 339  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 340  */
 341 static unsigned ext3_list_backups(struct super_block *sb, unsigned *three,
 342                                   unsigned *five, unsigned *seven)
 343 {
 344         unsigned *min = three;
 345         int mult = 3;
 346         unsigned ret;
 347
 348         if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
 349                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 350                 ret = *min;
 351                 *min += 1;
 352                 return ret;
 353         }
 354
 355         if (*five < *min) {
 356                 min = five;
 357                 mult = 5;
 358         }
 359         if (*seven < *min) {
 360                 min = seven;
 361                 mult = 7;
 362         }
 363
 364         ret = *min;
 365         *min *= mult;
 366
 367         return ret;
 368 }
 369
 370 /*
 371  * Check that all of the backup GDT blocks are held in the primary GDT block.
 372  * It is assumed that they are stored in group order.  Returns the number of
 373  * groups in current filesystem that have BACKUPS, or -ve error code.
 374  */
 375 static int verify_reserved_gdb(struct super_block *sb,
 376                                struct buffer_head *primary)
 377 {
 378         const ext3_fsblk_t blk = primary->b_blocknr;
 379         const unsigned long end = EXT3_SB(sb)->s_groups_count;
 380         unsigned three = 1;
 381         unsigned five = 5;
 382         unsigned seven = 7;
 383         unsigned grp;
 384         __le32 *p = (__le32 *)primary->b_data;
 385         int gdbackups = 0;
 386
 387         while ((grp = ext3_list_backups(sb, &three, &five, &seven)) < end) {
 388                 if (le32_to_cpu(*p++) != grp * EXT3_BLOCKS_PER_GROUP(sb) + blk){
 389                         ext3_warning(sb, __func__,
 390                                      "reserved GDT "E3FSBLK
 391                                      " missing grp %d ("E3FSBLK")",
 392                                      blk, grp,
 393                                      grp * EXT3_BLOCKS_PER_GROUP(sb) + blk);
 394                         return -EINVAL;
 395                 }
 396                 if (++gdbackups > EXT3_ADDR_PER_BLOCK(sb))
 397                         return -EFBIG;
 398         }
 399
 400         return gdbackups;
 401 }
 402
 403 /*
 404  * Called when we need to bring a reserved group descriptor table block into
 405  * use from the resize inode.  The primary copy of the new GDT block currently
 406  * is an indirect block (under the double indirect block in the resize inode).
 407  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 408  * block, in group order.  Even though we know all the block numbers we need,
 409  * we check to ensure that the resize inode has actually reserved these blocks.
 410  *
 411  * Don't need to update the block bitmaps because the blocks are still in use.
 412  *
 413  * We get all of the error cases out of the way, so that we are sure to not
 414  * fail once we start modifying the data on disk, because JBD has no rollback.
 415  */
 416 static int add_new_gdb(handle_t *handle, struct inode *inode,
 417                        struct ext3_new_group_data *input,
 418                        struct buffer_head **primary)
 419 {
 420         struct super_block *sb = inode->i_sb;
 421         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
 422         unsigned long gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 423         ext3_fsblk_t gdblock = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 424         struct buffer_head **o_group_desc, **n_group_desc;
 425         struct buffer_head *dind;
 426         int gdbackups;
 427         struct ext3_iloc iloc;
 428         __le32 *data;
 429         int err;
 430
 431         if (test_opt(sb, DEBUG))
 432                 printk(KERN_DEBUG
 433                        "EXT3-fs: ext3_add_new_gdb: adding group block %lu\n",
 434                        gdb_num);
 435
 436         /*
 437          * If we are not using the primary superblock/GDT copy don't resize,
 438          * because the user tools have no way of handling this.  Probably a
 439          * bad time to do it anyways.
 440          */
 441         if (EXT3_SB(sb)->s_sbh->b_blocknr !=
 442             le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) {
 443                 ext3_warning(sb, __func__,
 444                         "won't resize using backup superblock at %llu",
 445                         (unsigned long long)EXT3_SB(sb)->s_sbh->b_blocknr);
 446                 return -EPERM;
 447         }
 448
 449         *primary = sb_bread(sb, gdblock);
 450         if (!*primary)
 451                 return -EIO;
 452
 453         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 454                 err = gdbackups;
 455                 goto exit_bh;
 456         }
 457
 458         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 459         dind = sb_bread(sb, le32_to_cpu(*data));
 460         if (!dind) {
 461                 err = -EIO;
 462                 goto exit_bh;
 463         }
 464
 465         data = (__le32 *)dind->b_data;
 466         if (le32_to_cpu(data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)]) != gdblock) {
 467                 ext3_warning(sb, __func__,
 468                              "new group %u GDT block "E3FSBLK" not reserved",
 469                              input->group, gdblock);
 470                 err = -EINVAL;
 471                 goto exit_dind;
 472         }
 473
 474         if ((err = ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh)))
 475                 goto exit_dind;
 476
 477         if ((err = ext3_journal_get_write_access(handle, *primary)))
 478                 goto exit_sbh;
 479
 480         if ((err = ext3_journal_get_write_access(handle, dind)))
 481                 goto exit_primary;
 482
 483         /* ext3_reserve_inode_write() gets a reference on the iloc */
 484         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 485                 goto exit_dindj;
 486
 487         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 488                         GFP_NOFS);
 489         if (!n_group_desc) {
 490                 err = -ENOMEM;
 491                 ext3_warning (sb, __func__,
 492                               "not enough memory for %lu groups", gdb_num + 1);
 493                 goto exit_inode;
 494         }
 495
 496         /*
 497          * Finally, we have all of the possible failures behind us...
 498          *
 499          * Remove new GDT block from inode double-indirect block and clear out
 500          * the new GDT block for use (which also "frees" the backup GDT blocks
 501          * from the reserved inode).  We don't need to change the bitmaps for
 502          * these blocks, because they are marked as in-use from being in the
 503          * reserved inode, and will become GDT blocks (primary and backup).
 504          */
 505         data[gdb_num % EXT3_ADDR_PER_BLOCK(sb)] = 0;
 506         ext3_journal_dirty_metadata(handle, dind);
 507         brelse(dind);
 508         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 509         ext3_mark_iloc_dirty(handle, inode, &iloc);
 510         memset((*primary)->b_data, 0, sb->s_blocksize);
 511         ext3_journal_dirty_metadata(handle, *primary);
 512
 513         o_group_desc = EXT3_SB(sb)->s_group_desc;
 514         memcpy(n_group_desc, o_group_desc,
 515                EXT3_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 516         n_group_desc[gdb_num] = *primary;
 517         EXT3_SB(sb)->s_group_desc = n_group_desc;
 518         EXT3_SB(sb)->s_gdb_count++;
 519         kfree(o_group_desc);
 520
 521         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 522         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 523
 524         return 0;
 525
 526 exit_inode:
 527         //ext3_journal_release_buffer(handle, iloc.bh);
 528         brelse(iloc.bh);
 529 exit_dindj:
 530         //ext3_journal_release_buffer(handle, dind);
 531 exit_primary:
 532         //ext3_journal_release_buffer(handle, *primary);
 533 exit_sbh:
 534         //ext3_journal_release_buffer(handle, *primary);
 535 exit_dind:
 536         brelse(dind);
 537 exit_bh:
 538         brelse(*primary);
 539
 540         ext3_debug("leaving with error %d\n", err);
 541         return err;
 542 }
 543
 544 /*
 545  * Called when we are adding a new group which has a backup copy of each of
 546  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 547  * We need to add these reserved backup GDT blocks to the resize inode, so
 548  * that they are kept for future resizing and not allocated to files.
 549  *
 550  * Each reserved backup GDT block will go into a different indirect block.
 551  * The indirect blocks are actually the primary reserved GDT blocks,
 552  * so we know in advance what their block numbers are.  We only get the
 553  * double-indirect block to verify it is pointing to the primary reserved
 554  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 555  * backup GDT blocks are stored in their reserved primary GDT block.
 556  */
 557 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 558                               struct ext3_new_group_data *input)
 559 {
 560         struct super_block *sb = inode->i_sb;
 561         int reserved_gdb =le16_to_cpu(EXT3_SB(sb)->s_es->s_reserved_gdt_blocks);
 562         struct buffer_head **primary;
 563         struct buffer_head *dind;
 564         struct ext3_iloc iloc;
 565         ext3_fsblk_t blk;
 566         __le32 *data, *end;
 567         int gdbackups = 0;
 568         int res, i;
 569         int err;
 570
 571         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 572         if (!primary)
 573                 return -ENOMEM;
 574
 575         data = EXT3_I(inode)->i_data + EXT3_DIND_BLOCK;
 576         dind = sb_bread(sb, le32_to_cpu(*data));
 577         if (!dind) {
 578                 err = -EIO;
 579                 goto exit_free;
 580         }
 581
 582         blk = EXT3_SB(sb)->s_sbh->b_blocknr + 1 + EXT3_SB(sb)->s_gdb_count;
 583         data = (__le32 *)dind->b_data + (EXT3_SB(sb)->s_gdb_count %
 584                                          EXT3_ADDR_PER_BLOCK(sb));
 585         end = (__le32 *)dind->b_data + EXT3_ADDR_PER_BLOCK(sb);
 586
 587         /* Get each reserved primary GDT block and verify it holds backups */
 588         for (res = 0; res < reserved_gdb; res++, blk++) {
 589                 if (le32_to_cpu(*data) != blk) {
 590                         ext3_warning(sb, __func__,
 591                                      "reserved block "E3FSBLK
 592                                      " not at offset %ld",
 593                                      blk,
 594                                      (long)(data - (__le32 *)dind->b_data));
 595                         err = -EINVAL;
 596                         goto exit_bh;
 597                 }
 598                 primary[res] = sb_bread(sb, blk);
 599                 if (!primary[res]) {
 600                         err = -EIO;
 601                         goto exit_bh;
 602                 }
 603                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 604                         brelse(primary[res]);
 605                         err = gdbackups;
 606                         goto exit_bh;
 607                 }
 608                 if (++data >= end)
 609                         data = (__le32 *)dind->b_data;
 610         }
 611
 612         for (i = 0; i < reserved_gdb; i++) {
 613                 if ((err = ext3_journal_get_write_access(handle, primary[i]))) {
 614                         /*
 615                         int j;
 616                         for (j = 0; j < i; j++)
 617                                 ext3_journal_release_buffer(handle, primary[j]);
 618                          */
 619                         goto exit_bh;
 620                 }
 621         }
 622
 623         if ((err = ext3_reserve_inode_write(handle, inode, &iloc)))
 624                 goto exit_bh;
 625
 626         /*
 627          * Finally we can add each of the reserved backup GDT blocks from
 628          * the new group to its reserved primary GDT block.
 629          */
 630         blk = input->group * EXT3_BLOCKS_PER_GROUP(sb);
 631         for (i = 0; i < reserved_gdb; i++) {
 632                 int err2;
 633                 data = (__le32 *)primary[i]->b_data;
 634                 /* printk("reserving backup %lu[%u] = %lu\n",
 635                        primary[i]->b_blocknr, gdbackups,
 636                        blk + primary[i]->b_blocknr); */
 637                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 638                 err2 = ext3_journal_dirty_metadata(handle, primary[i]);
 639                 if (!err)
 640                         err = err2;
 641         }
 642         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 643         ext3_mark_iloc_dirty(handle, inode, &iloc);
 644
 645 exit_bh:
 646         while (--res >= 0)
 647                 brelse(primary[res]);
 648         brelse(dind);
 649
 650 exit_free:
 651         kfree(primary);
 652
 653         return err;
 654 }
 655
 656 /*
 657  * Update the backup copies of the ext3 metadata.  These don't need to be part
 658  * of the main resize transaction, because e2fsck will re-write them if there
 659  * is a problem (basically only OOM will cause a problem).  However, we
 660  * _should_ update the backups if possible, in case the primary gets trashed
 661  * for some reason and we need to run e2fsck from a backup superblock.  The
 662  * important part is that the new block and inode counts are in the backup
 663  * superblocks, and the location of the new group metadata in the GDT backups.
 664  *
 665  * We do not need take the s_resize_lock for this, because these
 666  * blocks are not otherwise touched by the filesystem code when it is
 667  * mounted.  We don't need to worry about last changing from
 668  * sbi->s_groups_count, because the worst that can happen is that we
 669  * do not copy the full number of backups at this time.  The resize
 670  * which changed s_groups_count will backup again.
 671  */
 672 static void update_backups(struct super_block *sb,
 673                            int blk_off, char *data, int size)
 674 {
 675         struct ext3_sb_info *sbi = EXT3_SB(sb);
 676         const unsigned long last = sbi->s_groups_count;
 677         const int bpg = EXT3_BLOCKS_PER_GROUP(sb);
 678         unsigned three = 1;
 679         unsigned five = 5;
 680         unsigned seven = 7;
 681         unsigned group;
 682         int rest = sb->s_blocksize - size;
 683         handle_t *handle;
 684         int err = 0, err2;
 685
 686         handle = ext3_journal_start_sb(sb, EXT3_MAX_TRANS_DATA);
 687         if (IS_ERR(handle)) {
 688                 group = 1;
 689                 err = PTR_ERR(handle);
 690                 goto exit_err;
 691         }
 692
 693         while ((group = ext3_list_backups(sb, &three, &five, &seven)) < last) {
 694                 struct buffer_head *bh;
 695
 696                 /* Out of journal space, and can't get more - abort - so sad */
 697                 if (handle->h_buffer_credits == 0 &&
 698                     ext3_journal_extend(handle, EXT3_MAX_TRANS_DATA) &&
 699                     (err = ext3_journal_restart(handle, EXT3_MAX_TRANS_DATA)))
 700                         break;
 701
 702                 bh = sb_getblk(sb, group * bpg + blk_off);
 703                 if (!bh) {
 704                         err = -EIO;
 705                         break;
 706                 }
 707                 ext3_debug("update metadata backup %#04lx\n",
 708                           (unsigned long)bh->b_blocknr);
 709                 if ((err = ext3_journal_get_write_access(handle, bh)))
 710                         break;
 711                 lock_buffer(bh);
 712                 memcpy(bh->b_data, data, size);
 713                 if (rest)
 714                         memset(bh->b_data + size, 0, rest);
 715                 set_buffer_uptodate(bh);
 716                 unlock_buffer(bh);
 717                 ext3_journal_dirty_metadata(handle, bh);
 718                 brelse(bh);
 719         }
 720         if ((err2 = ext3_journal_stop(handle)) && !err)
 721                 err = err2;
 722
 723         /*
 724          * Ugh! Need to have e2fsck write the backup copies.  It is too
 725          * late to revert the resize, we shouldn't fail just because of
 726          * the backup copies (they are only needed in case of corruption).
 727          *
 728          * However, if we got here we have a journal problem too, so we
 729          * can't really start a transaction to mark the superblock.
 730          * Chicken out and just set the flag on the hope it will be written
 731          * to disk, and if not - we will simply wait until next fsck.
 732          */
 733 exit_err:
 734         if (err) {
 735                 ext3_warning(sb, __func__,
 736                              "can't update backup for group %d (err %d), "
 737                              "forcing fsck on next reboot", group, err);
 738                 sbi->s_mount_state &= ~EXT3_VALID_FS;
 739                 sbi->s_es->s_state &= cpu_to_le16(~EXT3_VALID_FS);
 740                 mark_buffer_dirty(sbi->s_sbh);
 741         }
 742 }
 743
 744 /* Add group descriptor data to an existing or new group descriptor block.
 745  * Ensure we handle all possible error conditions _before_ we start modifying
 746  * the filesystem, because we cannot abort the transaction and not have it
 747  * write the data to disk.
 748  *
 749  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 750  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 751  *
 752  * We only need to hold the superblock lock while we are actually adding
 753  * in the new group's counts to the superblock.  Prior to that we have
 754  * not really "added" the group at all.  We re-check that we are still
 755  * adding in the last group in case things have changed since verifying.
 756  */
 757 int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input)
 758 {
 759         struct ext3_sb_info *sbi = EXT3_SB(sb);
 760         struct ext3_super_block *es = sbi->s_es;
 761         int reserved_gdb = ext3_bg_has_super(sb, input->group) ?
 762                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 763         struct buffer_head *primary = NULL;
 764         struct ext3_group_desc *gdp;
 765         struct inode *inode = NULL;
 766         handle_t *handle;
 767         int gdb_off, gdb_num;
 768         int err, err2;
 769
 770         gdb_num = input->group / EXT3_DESC_PER_BLOCK(sb);
 771         gdb_off = input->group % EXT3_DESC_PER_BLOCK(sb);
 772
 773         if (gdb_off == 0 && !EXT3_HAS_RO_COMPAT_FEATURE(sb,
 774                                         EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 775                 ext3_warning(sb, __func__,
 776                              "Can't resize non-sparse filesystem further");
 777                 return -EPERM;
 778         }
 779
 780         if (le32_to_cpu(es->s_blocks_count) + input->blocks_count <
 781             le32_to_cpu(es->s_blocks_count)) {
 782                 ext3_warning(sb, __func__, "blocks_count overflow\n");
 783                 return -EINVAL;
 784         }
 785
 786         if (le32_to_cpu(es->s_inodes_count) + EXT3_INODES_PER_GROUP(sb) <
 787             le32_to_cpu(es->s_inodes_count)) {
 788                 ext3_warning(sb, __func__, "inodes_count overflow\n");
 789                 return -EINVAL;
 790         }
 791
 792         if (reserved_gdb || gdb_off == 0) {
 793                 if (!EXT3_HAS_COMPAT_FEATURE(sb,
 794                                              EXT3_FEATURE_COMPAT_RESIZE_INODE)
 795                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
 796                         ext3_warning(sb, __func__,
 797                                      "No reserved GDT blocks, can't resize");
 798                         return -EPERM;
 799                 }
 800                 inode = ext3_iget(sb, EXT3_RESIZE_INO);
 801                 if (IS_ERR(inode)) {
 802                         ext3_warning(sb, __func__,
 803                                      "Error opening resize inode");
 804                         return PTR_ERR(inode);
 805                 }
 806         }
 807
 808         if ((err = verify_group_input(sb, input)))
 809                 goto exit_put;
 810
 811         if ((err = setup_new_group_blocks(sb, input)))
 812                 goto exit_put;
 813
 814         /*
 815          * We will always be modifying at least the superblock and a GDT
 816          * block.  If we are adding a group past the last current GDT block,
 817          * we will also modify the inode and the dindirect block.  If we
 818          * are adding a group with superblock/GDT backups  we will also
 819          * modify each of the reserved GDT dindirect blocks.
 820          */
 821         handle = ext3_journal_start_sb(sb,
 822                                        ext3_bg_has_super(sb, input->group) ?
 823                                        3 + reserved_gdb : 4);
 824         if (IS_ERR(handle)) {
 825                 err = PTR_ERR(handle);
 826                 goto exit_put;
 827         }
 828
 829         mutex_lock(&sbi->s_resize_lock);
 830         if (input->group != sbi->s_groups_count) {
 831                 ext3_warning(sb, __func__,
 832                              "multiple resizers run on filesystem!");
 833                 err = -EBUSY;
 834                 goto exit_journal;
 835         }
 836
 837         if ((err = ext3_journal_get_write_access(handle, sbi->s_sbh)))
 838                 goto exit_journal;
 839
 840         /*
 841          * We will only either add reserved group blocks to a backup group
 842          * or remove reserved blocks for the first group in a new group block.
 843          * Doing both would be mean more complex code, and sane people don't
 844          * use non-sparse filesystems anymore.  This is already checked above.
 845          */
 846         if (gdb_off) {
 847                 primary = sbi->s_group_desc[gdb_num];
 848                 if ((err = ext3_journal_get_write_access(handle, primary)))
 849                         goto exit_journal;
 850
 851                 if (reserved_gdb && ext3_bg_num_gdb(sb, input->group) &&
 852                     (err = reserve_backup_gdb(handle, inode, input)))
 853                         goto exit_journal;
 854         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 855                 goto exit_journal;
 856
 857         /*
 858          * OK, now we've set up the new group.  Time to make it active.
 859          *
 860          * We do not lock all allocations via s_resize_lock
 861          * so we have to be safe wrt. concurrent accesses the group
 862          * data.  So we need to be careful to set all of the relevant
 863          * group descriptor data etc. *before* we enable the group.
 864          *
 865          * The key field here is sbi->s_groups_count: as long as
 866          * that retains its old value, nobody is going to access the new
 867          * group.
 868          *
 869          * So first we update all the descriptor metadata for the new
 870          * group; then we update the total disk blocks count; then we
 871          * update the groups count to enable the group; then finally we
 872          * update the free space counts so that the system can start
 873          * using the new disk blocks.
 874          */
 875
 876         /* Update group descriptor block for new group */
 877         gdp = (struct ext3_group_desc *)primary->b_data + gdb_off;
 878
 879         gdp->bg_block_bitmap = cpu_to_le32(input->block_bitmap);
 880         gdp->bg_inode_bitmap = cpu_to_le32(input->inode_bitmap);
 881         gdp->bg_inode_table = cpu_to_le32(input->inode_table);
 882         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 883         gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
 884
 885         /*
 886          * Make the new blocks and inodes valid next.  We do this before
 887          * increasing the group count so that once the group is enabled,
 888          * all of its blocks and inodes are already valid.
 889          *
 890          * We always allocate group-by-group, then block-by-block or
 891          * inode-by-inode within a group, so enabling these
 892          * blocks/inodes before the group is live won't actually let us
 893          * allocate the new space yet.
 894          */
 895         le32_add_cpu(&es->s_blocks_count, input->blocks_count);
 896         le32_add_cpu(&es->s_inodes_count, EXT3_INODES_PER_GROUP(sb));
 897
 898         /*
 899          * We need to protect s_groups_count against other CPUs seeing
 900          * inconsistent state in the superblock.
 901          *
 902          * The precise rules we use are:
 903          *
 904          * * Writers of s_groups_count *must* hold s_resize_lock
 905          * AND
 906          * * Writers must perform a smp_wmb() after updating all dependent
 907          *   data and before modifying the groups count
 908          *
 909          * * Readers must hold s_resize_lock over the access
 910          * OR
 911          * * Readers must perform an smp_rmb() after reading the groups count
 912          *   and before reading any dependent data.
 913          *
 914          * NB. These rules can be relaxed when checking the group count
 915          * while freeing data, as we can only allocate from a block
 916          * group after serialising against the group count, and we can
 917          * only then free after serialising in turn against that
 918          * allocation.
 919          */
 920         smp_wmb();
 921
 922         /* Update the global fs size fields */
 923         sbi->s_groups_count++;
 924
 925         ext3_journal_dirty_metadata(handle, primary);
 926
 927         /* Update the reserved block counts only once the new group is
 928          * active. */
 929         le32_add_cpu(&es->s_r_blocks_count, input->reserved_blocks);
 930
 931         /* Update the free space counts */
 932         percpu_counter_add(&sbi->s_freeblocks_counter,
 933                            input->free_blocks_count);
 934         percpu_counter_add(&sbi->s_freeinodes_counter,
 935                            EXT3_INODES_PER_GROUP(sb));
 936
 937         ext3_journal_dirty_metadata(handle, sbi->s_sbh);
 938
 939 exit_journal:
 940         mutex_unlock(&sbi->s_resize_lock);
 941         if ((err2 = ext3_journal_stop(handle)) && !err)
 942                 err = err2;
 943         if (!err) {
 944                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 945                                sizeof(struct ext3_super_block));
 946                 update_backups(sb, primary->b_blocknr, primary->b_data,
 947                                primary->b_size);
 948         }
 949 exit_put:
 950         iput(inode);
 951         return err;
 952 } /* ext3_group_add */
 953
 954 /* Extend the filesystem to the new number of blocks specified.  This entry
 955  * point is only used to extend the current filesystem to the end of the last
 956  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 957  * for emergencies (because it has no dependencies on reserved blocks).
 958  *
 959  * If we _really_ wanted, we could use default values to call ext3_group_add()
 960  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 961  * GDT blocks are reserved to grow to the desired size.
 962  */
 963 int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es,
 964                       ext3_fsblk_t n_blocks_count)
 965 {
 966         ext3_fsblk_t o_blocks_count;
 967         unsigned long o_groups_count;
 968         ext3_grpblk_t last;
 969         ext3_grpblk_t add;
 970         struct buffer_head * bh;
 971         handle_t *handle;
 972         int err;
 973         unsigned long freed_blocks;
 974
 975         /* We don't need to worry about locking wrt other resizers just
 976          * yet: we're going to revalidate es->s_blocks_count after
 977          * taking the s_resize_lock below. */
 978         o_blocks_count = le32_to_cpu(es->s_blocks_count);
 979         o_groups_count = EXT3_SB(sb)->s_groups_count;
 980
 981         if (test_opt(sb, DEBUG))
 982                 printk(KERN_DEBUG "EXT3-fs: extending last group from "E3FSBLK" uto "E3FSBLK" blocks\n",
 983                        o_blocks_count, n_blocks_count);
 984
 985         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 986                 return 0;
 987
 988         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
 989                 printk(KERN_ERR "EXT3-fs: filesystem on %s:"
 990                         " too large to resize to %lu blocks safely\n",
 991                         sb->s_id, n_blocks_count);
 992                 if (sizeof(sector_t) < 8)
 993                         ext3_warning(sb, __func__,
 994                         "CONFIG_LBDAF not enabled\n");
 995                 return -EINVAL;
 996         }
 997
 998         if (n_blocks_count < o_blocks_count) {
 999                 ext3_warning(sb, __func__,
1000                              "can't shrink FS - resize aborted");
1001                 return -EBUSY;
1002         }
1003
1004         /* Handle the remaining blocks in the last group only. */
1005         last = (o_blocks_count - le32_to_cpu(es->s_first_data_block)) %
1006                 EXT3_BLOCKS_PER_GROUP(sb);
1007
1008         if (last == 0) {
1009                 ext3_warning(sb, __func__,
1010                              "need to use ext2online to resize further");
1011                 return -EPERM;
1012         }
1013
1014         add = EXT3_BLOCKS_PER_GROUP(sb) - last;
1015
1016         if (o_blocks_count + add < o_blocks_count) {
1017                 ext3_warning(sb, __func__, "blocks_count overflow");
1018                 return -EINVAL;
1019         }
1020
1021         if (o_blocks_count + add > n_blocks_count)
1022                 add = n_blocks_count - o_blocks_count;
1023
1024         if (o_blocks_count + add < n_blocks_count)
1025                 ext3_warning(sb, __func__,
1026                              "will only finish group ("E3FSBLK
1027                              " blocks, %u new)",
1028                              o_blocks_count + add, add);
1029
1030         /* See if the device is actually as big as what was requested */
1031         bh = sb_bread(sb, o_blocks_count + add -1);
1032         if (!bh) {
1033                 ext3_warning(sb, __func__,
1034                              "can't read last block, resize aborted");
1035                 return -ENOSPC;
1036         }
1037         brelse(bh);
1038
1039         /* We will update the superblock, one block bitmap, and
1040          * one group descriptor via ext3_free_blocks().
1041          */
1042         handle = ext3_journal_start_sb(sb, 3);
1043         if (IS_ERR(handle)) {
1044                 err = PTR_ERR(handle);
1045                 ext3_warning(sb, __func__, "error %d on journal start",err);
1046                 goto exit_put;
1047         }
1048
1049         mutex_lock(&EXT3_SB(sb)->s_resize_lock);
1050         if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
1051                 ext3_warning(sb, __func__,
1052                              "multiple resizers run on filesystem!");
1053                 mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1054                 ext3_journal_stop(handle);
1055                 err = -EBUSY;
1056                 goto exit_put;
1057         }
1058
1059         if ((err = ext3_journal_get_write_access(handle,
1060                                                  EXT3_SB(sb)->s_sbh))) {
1061                 ext3_warning(sb, __func__,
1062                              "error %d on journal write access", err);
1063                 mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1064                 ext3_journal_stop(handle);
1065                 goto exit_put;
1066         }
1067         es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
1068         ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
1069         mutex_unlock(&EXT3_SB(sb)->s_resize_lock);
1070         ext3_debug("freeing blocks %lu through "E3FSBLK"\n", o_blocks_count,
1071                    o_blocks_count + add);
1072         ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1073         ext3_debug("freed blocks "E3FSBLK" through "E3FSBLK"\n", o_blocks_count,
1074                    o_blocks_count + add);
1075         if ((err = ext3_journal_stop(handle)))
1076                 goto exit_put;
1077         if (test_opt(sb, DEBUG))
1078                 printk(KERN_DEBUG "EXT3-fs: extended group to %u blocks\n",
1079                        le32_to_cpu(es->s_blocks_count));
1080         update_backups(sb, EXT3_SB(sb)->s_sbh->b_blocknr, (char *)es,
1081                        sizeof(struct ext3_super_block));
1082 exit_put:
1083         return err;
1084 } /* ext3_group_extend */