fs/ext4/resize.c

   1 /*
   2  *  linux/fs/ext4/resize.c
   3  *
   4  * Support for resizing an ext4 filesystem while it is mounted.
   5  *
   6  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
   7  *
   8  * This could probably be made into a module, because it is not often in use.
   9  */
  10
  11
  12 #define EXT4FS_DEBUG
  13
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16
  17 #include "ext4_jbd2.h"
  18
  19 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  20 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  21
  22 static int verify_group_input(struct super_block *sb,
  23                               struct ext4_new_group_data *input)
  24 {
  25         struct ext4_sb_info *sbi = EXT4_SB(sb);
  26         struct ext4_super_block *es = sbi->s_es;
  27         ext4_fsblk_t start = ext4_blocks_count(es);
  28         ext4_fsblk_t end = start + input->blocks_count;
  29         ext4_group_t group = input->group;
  30         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  31         unsigned overhead = ext4_bg_has_super(sb, group) ?
  32                 (1 + ext4_bg_num_gdb(sb, group) +
  33                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  34         ext4_fsblk_t metaend = start + overhead;
  35         struct buffer_head *bh = NULL;
  36         ext4_grpblk_t free_blocks_count, offset;
  37         int err = -EINVAL;
  38
  39         input->free_blocks_count = free_blocks_count =
  40                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  41
  42         if (test_opt(sb, DEBUG))
  43                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
  44                        "(%d free, %u reserved)\n",
  45                        ext4_bg_has_super(sb, input->group) ? "normal" :
  46                        "no-super", input->group, input->blocks_count,
  47                        free_blocks_count, input->reserved_blocks);
  48
  49         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
  50         if (group != sbi->s_groups_count)
  51                 ext4_warning(sb, __func__,
  52                              "Cannot add at group %u (only %u groups)",
  53                              input->group, sbi->s_groups_count);
  54         else if (offset != 0)
  55                         ext4_warning(sb, __func__, "Last group not full");
  56         else if (input->reserved_blocks > input->blocks_count / 5)
  57                 ext4_warning(sb, __func__, "Reserved blocks too high (%u)",
  58                              input->reserved_blocks);
  59         else if (free_blocks_count < 0)
  60                 ext4_warning(sb, __func__, "Bad blocks count %u",
  61                              input->blocks_count);
  62         else if (!(bh = sb_bread(sb, end - 1)))
  63                 ext4_warning(sb, __func__,
  64                              "Cannot read last block (%llu)",
  65                              end - 1);
  66         else if (outside(input->block_bitmap, start, end))
  67                 ext4_warning(sb, __func__,
  68                              "Block bitmap not in group (block %llu)",
  69                              (unsigned long long)input->block_bitmap);
  70         else if (outside(input->inode_bitmap, start, end))
  71                 ext4_warning(sb, __func__,
  72                              "Inode bitmap not in group (block %llu)",
  73                              (unsigned long long)input->inode_bitmap);
  74         else if (outside(input->inode_table, start, end) ||
  75                  outside(itend - 1, start, end))
  76                 ext4_warning(sb, __func__,
  77                              "Inode table not in group (blocks %llu-%llu)",
  78                              (unsigned long long)input->inode_table, itend - 1);
  79         else if (input->inode_bitmap == input->block_bitmap)
  80                 ext4_warning(sb, __func__,
  81                              "Block bitmap same as inode bitmap (%llu)",
  82                              (unsigned long long)input->block_bitmap);
  83         else if (inside(input->block_bitmap, input->inode_table, itend))
  84                 ext4_warning(sb, __func__,
  85                              "Block bitmap (%llu) in inode table (%llu-%llu)",
  86                              (unsigned long long)input->block_bitmap,
  87                              (unsigned long long)input->inode_table, itend - 1);
  88         else if (inside(input->inode_bitmap, input->inode_table, itend))
  89                 ext4_warning(sb, __func__,
  90                              "Inode bitmap (%llu) in inode table (%llu-%llu)",
  91                              (unsigned long long)input->inode_bitmap,
  92                              (unsigned long long)input->inode_table, itend - 1);
  93         else if (inside(input->block_bitmap, start, metaend))
  94                 ext4_warning(sb, __func__,
  95                              "Block bitmap (%llu) in GDT table"
  96                              " (%llu-%llu)",
  97                              (unsigned long long)input->block_bitmap,
  98                              start, metaend - 1);
  99         else if (inside(input->inode_bitmap, start, metaend))
 100                 ext4_warning(sb, __func__,
 101                              "Inode bitmap (%llu) in GDT table"
 102                              " (%llu-%llu)",
 103                              (unsigned long long)input->inode_bitmap,
 104                              start, metaend - 1);
 105         else if (inside(input->inode_table, start, metaend) ||
 106                  inside(itend - 1, start, metaend))
 107                 ext4_warning(sb, __func__,
 108                              "Inode table (%llu-%llu) overlaps"
 109                              "GDT table (%llu-%llu)",
 110                              (unsigned long long)input->inode_table,
 111                              itend - 1, start, metaend - 1);
 112         else
 113                 err = 0;
 114         brelse(bh);
 115
 116         return err;
 117 }
 118
 119 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 120                                   ext4_fsblk_t blk)
 121 {
 122         struct buffer_head *bh;
 123         int err;
 124
 125         bh = sb_getblk(sb, blk);
 126         if (!bh)
 127                 return ERR_PTR(-EIO);
 128         if ((err = ext4_journal_get_write_access(handle, bh))) {
 129                 brelse(bh);
 130                 bh = ERR_PTR(err);
 131         } else {
 132                 lock_buffer(bh);
 133                 memset(bh->b_data, 0, sb->s_blocksize);
 134                 set_buffer_uptodate(bh);
 135                 unlock_buffer(bh);
 136         }
 137
 138         return bh;
 139 }
 140
 141 /*
 142  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 143  * If that fails, restart the transaction & regain write access for the
 144  * buffer head which is used for block_bitmap modifications.
 145  */
 146 static int extend_or_restart_transaction(handle_t *handle, int thresh,
 147                                          struct buffer_head *bh)
 148 {
 149         int err;
 150
 151         if (ext4_handle_has_enough_credits(handle, thresh))
 152                 return 0;
 153
 154         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 155         if (err < 0)
 156                 return err;
 157         if (err) {
 158                 if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 159                         return err;
 160                 if ((err = ext4_journal_get_write_access(handle, bh)))
 161                         return err;
 162         }
 163
 164         return 0;
 165 }
 166
 167 /*
 168  * Set up the block and inode bitmaps, and the inode table for the new group.
 169  * This doesn't need to be part of the main transaction, since we are only
 170  * changing blocks outside the actual filesystem.  We still do journaling to
 171  * ensure the recovery is correct in case of a failure just after resize.
 172  * If any part of this fails, we simply abort the resize.
 173  */
 174 static int setup_new_group_blocks(struct super_block *sb,
 175                                   struct ext4_new_group_data *input)
 176 {
 177         struct ext4_sb_info *sbi = EXT4_SB(sb);
 178         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
 179         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 180                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
 181         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
 182         struct buffer_head *bh;
 183         handle_t *handle;
 184         ext4_fsblk_t block;
 185         ext4_grpblk_t bit;
 186         int i;
 187         int err = 0, err2;
 188
 189         /* This transaction may be extended/restarted along the way */
 190         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 191
 192         if (IS_ERR(handle))
 193                 return PTR_ERR(handle);
 194
 195         mutex_lock(&sbi->s_resize_lock);
 196         if (input->group != sbi->s_groups_count) {
 197                 err = -EBUSY;
 198                 goto exit_journal;
 199         }
 200
 201         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
 202                 err = PTR_ERR(bh);
 203                 goto exit_journal;
 204         }
 205
 206         if (ext4_bg_has_super(sb, input->group)) {
 207                 ext4_debug("mark backup superblock %#04llx (+0)\n", start);
 208                 ext4_set_bit(0, bh->b_data);
 209         }
 210
 211         /* Copy all of the GDT blocks into the backup in this group */
 212         for (i = 0, bit = 1, block = start + 1;
 213              i < gdblocks; i++, block++, bit++) {
 214                 struct buffer_head *gdb;
 215
 216                 ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
 217
 218                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 219                         goto exit_bh;
 220
 221                 gdb = sb_getblk(sb, block);
 222                 if (!gdb) {
 223                         err = -EIO;
 224                         goto exit_bh;
 225                 }
 226                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
 227                         brelse(gdb);
 228                         goto exit_bh;
 229                 }
 230                 lock_buffer(gdb);
 231                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
 232                 set_buffer_uptodate(gdb);
 233                 unlock_buffer(gdb);
 234                 ext4_handle_dirty_metadata(handle, NULL, gdb);
 235                 ext4_set_bit(bit, bh->b_data);
 236                 brelse(gdb);
 237         }
 238
 239         /* Zero out all of the reserved backup group descriptor table blocks */
 240         for (i = 0, bit = gdblocks + 1, block = start + bit;
 241              i < reserved_gdb; i++, block++, bit++) {
 242                 struct buffer_head *gdb;
 243
 244                 ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
 245
 246                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 247                         goto exit_bh;
 248
 249                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
 250                         err = PTR_ERR(bh);
 251                         goto exit_bh;
 252                 }
 253                 ext4_handle_dirty_metadata(handle, NULL, gdb);
 254                 ext4_set_bit(bit, bh->b_data);
 255                 brelse(gdb);
 256         }
 257         ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
 258                    input->block_bitmap - start);
 259         ext4_set_bit(input->block_bitmap - start, bh->b_data);
 260         ext4_debug("mark inode bitmap %#04llx (+%llu)\n", input->inode_bitmap,
 261                    input->inode_bitmap - start);
 262         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
 263
 264         /* Zero out all of the inode table blocks */
 265         for (i = 0, block = input->inode_table, bit = block - start;
 266              i < sbi->s_itb_per_group; i++, bit++, block++) {
 267                 struct buffer_head *it;
 268
 269                 ext4_debug("clear inode block %#04llx (+%d)\n", block, bit);
 270
 271                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
 272                         goto exit_bh;
 273
 274                 if (IS_ERR(it = bclean(handle, sb, block))) {
 275                         err = PTR_ERR(it);
 276                         goto exit_bh;
 277                 }
 278                 ext4_handle_dirty_metadata(handle, NULL, it);
 279                 brelse(it);
 280                 ext4_set_bit(bit, bh->b_data);
 281         }
 282
 283         if ((err = extend_or_restart_transaction(handle, 2, bh)))
 284                 goto exit_bh;
 285
 286         mark_bitmap_end(input->blocks_count, sb->s_blocksize * 8, bh->b_data);
 287         ext4_handle_dirty_metadata(handle, NULL, bh);
 288         brelse(bh);
 289         /* Mark unused entries in inode bitmap used */
 290         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
 291                    input->inode_bitmap, input->inode_bitmap - start);
 292         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
 293                 err = PTR_ERR(bh);
 294                 goto exit_journal;
 295         }
 296
 297         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
 298                         bh->b_data);
 299         ext4_handle_dirty_metadata(handle, NULL, bh);
 300 exit_bh:
 301         brelse(bh);
 302
 303 exit_journal:
 304         mutex_unlock(&sbi->s_resize_lock);
 305         if ((err2 = ext4_journal_stop(handle)) && !err)
 306                 err = err2;
 307
 308         return err;
 309 }
 310
 311 /*
 312  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 313  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 314  * calling this for the first time.  In a sparse filesystem it will be the
 315  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 316  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 317  */
 318 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 319                                   unsigned *five, unsigned *seven)
 320 {
 321         unsigned *min = three;
 322         int mult = 3;
 323         unsigned ret;
 324
 325         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 326                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 327                 ret = *min;
 328                 *min += 1;
 329                 return ret;
 330         }
 331
 332         if (*five < *min) {
 333                 min = five;
 334                 mult = 5;
 335         }
 336         if (*seven < *min) {
 337                 min = seven;
 338                 mult = 7;
 339         }
 340
 341         ret = *min;
 342         *min *= mult;
 343
 344         return ret;
 345 }
 346
 347 /*
 348  * Check that all of the backup GDT blocks are held in the primary GDT block.
 349  * It is assumed that they are stored in group order.  Returns the number of
 350  * groups in current filesystem that have BACKUPS, or -ve error code.
 351  */
 352 static int verify_reserved_gdb(struct super_block *sb,
 353                                struct buffer_head *primary)
 354 {
 355         const ext4_fsblk_t blk = primary->b_blocknr;
 356         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
 357         unsigned three = 1;
 358         unsigned five = 5;
 359         unsigned seven = 7;
 360         unsigned grp;
 361         __le32 *p = (__le32 *)primary->b_data;
 362         int gdbackups = 0;
 363
 364         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 365                 if (le32_to_cpu(*p++) !=
 366                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 367                         ext4_warning(sb, __func__,
 368                                      "reserved GDT %llu"
 369                                      " missing grp %d (%llu)",
 370                                      blk, grp,
 371                                      grp *
 372                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 373                                      blk);
 374                         return -EINVAL;
 375                 }
 376                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 377                         return -EFBIG;
 378         }
 379
 380         return gdbackups;
 381 }
 382
 383 /*
 384  * Called when we need to bring a reserved group descriptor table block into
 385  * use from the resize inode.  The primary copy of the new GDT block currently
 386  * is an indirect block (under the double indirect block in the resize inode).
 387  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 388  * block, in group order.  Even though we know all the block numbers we need,
 389  * we check to ensure that the resize inode has actually reserved these blocks.
 390  *
 391  * Don't need to update the block bitmaps because the blocks are still in use.
 392  *
 393  * We get all of the error cases out of the way, so that we are sure to not
 394  * fail once we start modifying the data on disk, because JBD has no rollback.
 395  */
 396 static int add_new_gdb(handle_t *handle, struct inode *inode,
 397                        struct ext4_new_group_data *input,
 398                        struct buffer_head **primary)
 399 {
 400         struct super_block *sb = inode->i_sb;
 401         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 402         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 403         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 404         struct buffer_head **o_group_desc, **n_group_desc;
 405         struct buffer_head *dind;
 406         int gdbackups;
 407         struct ext4_iloc iloc;
 408         __le32 *data;
 409         int err;
 410
 411         if (test_opt(sb, DEBUG))
 412                 printk(KERN_DEBUG
 413                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 414                        gdb_num);
 415
 416         /*
 417          * If we are not using the primary superblock/GDT copy don't resize,
 418          * because the user tools have no way of handling this.  Probably a
 419          * bad time to do it anyways.
 420          */
 421         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 422             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 423                 ext4_warning(sb, __func__,
 424                         "won't resize using backup superblock at %llu",
 425                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 426                 return -EPERM;
 427         }
 428
 429         *primary = sb_bread(sb, gdblock);
 430         if (!*primary)
 431                 return -EIO;
 432
 433         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
 434                 err = gdbackups;
 435                 goto exit_bh;
 436         }
 437
 438         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 439         dind = sb_bread(sb, le32_to_cpu(*data));
 440         if (!dind) {
 441                 err = -EIO;
 442                 goto exit_bh;
 443         }
 444
 445         data = (__le32 *)dind->b_data;
 446         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 447                 ext4_warning(sb, __func__,
 448                              "new group %u GDT block %llu not reserved",
 449                              input->group, gdblock);
 450                 err = -EINVAL;
 451                 goto exit_dind;
 452         }
 453
 454         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
 455                 goto exit_dind;
 456
 457         if ((err = ext4_journal_get_write_access(handle, *primary)))
 458                 goto exit_sbh;
 459
 460         if ((err = ext4_journal_get_write_access(handle, dind)))
 461                 goto exit_primary;
 462
 463         /* ext4_reserve_inode_write() gets a reference on the iloc */
 464         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 465                 goto exit_dindj;
 466
 467         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
 468                         GFP_NOFS);
 469         if (!n_group_desc) {
 470                 err = -ENOMEM;
 471                 ext4_warning(sb, __func__,
 472                               "not enough memory for %lu groups", gdb_num + 1);
 473                 goto exit_inode;
 474         }
 475
 476         /*
 477          * Finally, we have all of the possible failures behind us...
 478          *
 479          * Remove new GDT block from inode double-indirect block and clear out
 480          * the new GDT block for use (which also "frees" the backup GDT blocks
 481          * from the reserved inode).  We don't need to change the bitmaps for
 482          * these blocks, because they are marked as in-use from being in the
 483          * reserved inode, and will become GDT blocks (primary and backup).
 484          */
 485         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 486         ext4_handle_dirty_metadata(handle, NULL, dind);
 487         brelse(dind);
 488         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 489         ext4_mark_iloc_dirty(handle, inode, &iloc);
 490         memset((*primary)->b_data, 0, sb->s_blocksize);
 491         ext4_handle_dirty_metadata(handle, NULL, *primary);
 492
 493         o_group_desc = EXT4_SB(sb)->s_group_desc;
 494         memcpy(n_group_desc, o_group_desc,
 495                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 496         n_group_desc[gdb_num] = *primary;
 497         EXT4_SB(sb)->s_group_desc = n_group_desc;
 498         EXT4_SB(sb)->s_gdb_count++;
 499         kfree(o_group_desc);
 500
 501         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 502         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 503
 504         return 0;
 505
 506 exit_inode:
 507         /* ext4_journal_release_buffer(handle, iloc.bh); */
 508         brelse(iloc.bh);
 509 exit_dindj:
 510         /* ext4_journal_release_buffer(handle, dind); */
 511 exit_primary:
 512         /* ext4_journal_release_buffer(handle, *primary); */
 513 exit_sbh:
 514         /* ext4_journal_release_buffer(handle, *primary); */
 515 exit_dind:
 516         brelse(dind);
 517 exit_bh:
 518         brelse(*primary);
 519
 520         ext4_debug("leaving with error %d\n", err);
 521         return err;
 522 }
 523
 524 /*
 525  * Called when we are adding a new group which has a backup copy of each of
 526  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 527  * We need to add these reserved backup GDT blocks to the resize inode, so
 528  * that they are kept for future resizing and not allocated to files.
 529  *
 530  * Each reserved backup GDT block will go into a different indirect block.
 531  * The indirect blocks are actually the primary reserved GDT blocks,
 532  * so we know in advance what their block numbers are.  We only get the
 533  * double-indirect block to verify it is pointing to the primary reserved
 534  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 535  * backup GDT blocks are stored in their reserved primary GDT block.
 536  */
 537 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 538                               struct ext4_new_group_data *input)
 539 {
 540         struct super_block *sb = inode->i_sb;
 541         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 542         struct buffer_head **primary;
 543         struct buffer_head *dind;
 544         struct ext4_iloc iloc;
 545         ext4_fsblk_t blk;
 546         __le32 *data, *end;
 547         int gdbackups = 0;
 548         int res, i;
 549         int err;
 550
 551         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 552         if (!primary)
 553                 return -ENOMEM;
 554
 555         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 556         dind = sb_bread(sb, le32_to_cpu(*data));
 557         if (!dind) {
 558                 err = -EIO;
 559                 goto exit_free;
 560         }
 561
 562         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 563         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 564                                          EXT4_ADDR_PER_BLOCK(sb));
 565         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 566
 567         /* Get each reserved primary GDT block and verify it holds backups */
 568         for (res = 0; res < reserved_gdb; res++, blk++) {
 569                 if (le32_to_cpu(*data) != blk) {
 570                         ext4_warning(sb, __func__,
 571                                      "reserved block %llu"
 572                                      " not at offset %ld",
 573                                      blk,
 574                                      (long)(data - (__le32 *)dind->b_data));
 575                         err = -EINVAL;
 576                         goto exit_bh;
 577                 }
 578                 primary[res] = sb_bread(sb, blk);
 579                 if (!primary[res]) {
 580                         err = -EIO;
 581                         goto exit_bh;
 582                 }
 583                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
 584                         brelse(primary[res]);
 585                         err = gdbackups;
 586                         goto exit_bh;
 587                 }
 588                 if (++data >= end)
 589                         data = (__le32 *)dind->b_data;
 590         }
 591
 592         for (i = 0; i < reserved_gdb; i++) {
 593                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 594                         /*
 595                         int j;
 596                         for (j = 0; j < i; j++)
 597                                 ext4_journal_release_buffer(handle, primary[j]);
 598                          */
 599                         goto exit_bh;
 600                 }
 601         }
 602
 603         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 604                 goto exit_bh;
 605
 606         /*
 607          * Finally we can add each of the reserved backup GDT blocks from
 608          * the new group to its reserved primary GDT block.
 609          */
 610         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
 611         for (i = 0; i < reserved_gdb; i++) {
 612                 int err2;
 613                 data = (__le32 *)primary[i]->b_data;
 614                 /* printk("reserving backup %lu[%u] = %lu\n",
 615                        primary[i]->b_blocknr, gdbackups,
 616                        blk + primary[i]->b_blocknr); */
 617                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 618                 err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
 619                 if (!err)
 620                         err = err2;
 621         }
 622         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 623         ext4_mark_iloc_dirty(handle, inode, &iloc);
 624
 625 exit_bh:
 626         while (--res >= 0)
 627                 brelse(primary[res]);
 628         brelse(dind);
 629
 630 exit_free:
 631         kfree(primary);
 632
 633         return err;
 634 }
 635
 636 /*
 637  * Update the backup copies of the ext4 metadata.  These don't need to be part
 638  * of the main resize transaction, because e2fsck will re-write them if there
 639  * is a problem (basically only OOM will cause a problem).  However, we
 640  * _should_ update the backups if possible, in case the primary gets trashed
 641  * for some reason and we need to run e2fsck from a backup superblock.  The
 642  * important part is that the new block and inode counts are in the backup
 643  * superblocks, and the location of the new group metadata in the GDT backups.
 644  *
 645  * We do not need take the s_resize_lock for this, because these
 646  * blocks are not otherwise touched by the filesystem code when it is
 647  * mounted.  We don't need to worry about last changing from
 648  * sbi->s_groups_count, because the worst that can happen is that we
 649  * do not copy the full number of backups at this time.  The resize
 650  * which changed s_groups_count will backup again.
 651  */
 652 static void update_backups(struct super_block *sb,
 653                            int blk_off, char *data, int size)
 654 {
 655         struct ext4_sb_info *sbi = EXT4_SB(sb);
 656         const ext4_group_t last = sbi->s_groups_count;
 657         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 658         unsigned three = 1;
 659         unsigned five = 5;
 660         unsigned seven = 7;
 661         ext4_group_t group;
 662         int rest = sb->s_blocksize - size;
 663         handle_t *handle;
 664         int err = 0, err2;
 665
 666         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 667         if (IS_ERR(handle)) {
 668                 group = 1;
 669                 err = PTR_ERR(handle);
 670                 goto exit_err;
 671         }
 672
 673         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 674                 struct buffer_head *bh;
 675
 676                 /* Out of journal space, and can't get more - abort - so sad */
 677                 if (ext4_handle_valid(handle) &&
 678                     handle->h_buffer_credits == 0 &&
 679                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 680                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 681                         break;
 682
 683                 bh = sb_getblk(sb, group * bpg + blk_off);
 684                 if (!bh) {
 685                         err = -EIO;
 686                         break;
 687                 }
 688                 ext4_debug("update metadata backup %#04lx\n",
 689                           (unsigned long)bh->b_blocknr);
 690                 if ((err = ext4_journal_get_write_access(handle, bh)))
 691                         break;
 692                 lock_buffer(bh);
 693                 memcpy(bh->b_data, data, size);
 694                 if (rest)
 695                         memset(bh->b_data + size, 0, rest);
 696                 set_buffer_uptodate(bh);
 697                 unlock_buffer(bh);
 698                 ext4_handle_dirty_metadata(handle, NULL, bh);
 699                 brelse(bh);
 700         }
 701         if ((err2 = ext4_journal_stop(handle)) && !err)
 702                 err = err2;
 703
 704         /*
 705          * Ugh! Need to have e2fsck write the backup copies.  It is too
 706          * late to revert the resize, we shouldn't fail just because of
 707          * the backup copies (they are only needed in case of corruption).
 708          *
 709          * However, if we got here we have a journal problem too, so we
 710          * can't really start a transaction to mark the superblock.
 711          * Chicken out and just set the flag on the hope it will be written
 712          * to disk, and if not - we will simply wait until next fsck.
 713          */
 714 exit_err:
 715         if (err) {
 716                 ext4_warning(sb, __func__,
 717                              "can't update backup for group %u (err %d), "
 718                              "forcing fsck on next reboot", group, err);
 719                 sbi->s_mount_state &= ~EXT4_VALID_FS;
 720                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
 721                 mark_buffer_dirty(sbi->s_sbh);
 722         }
 723 }
 724
 725 /* Add group descriptor data to an existing or new group descriptor block.
 726  * Ensure we handle all possible error conditions _before_ we start modifying
 727  * the filesystem, because we cannot abort the transaction and not have it
 728  * write the data to disk.
 729  *
 730  * If we are on a GDT block boundary, we need to get the reserved GDT block.
 731  * Otherwise, we may need to add backup GDT blocks for a sparse group.
 732  *
 733  * We only need to hold the superblock lock while we are actually adding
 734  * in the new group's counts to the superblock.  Prior to that we have
 735  * not really "added" the group at all.  We re-check that we are still
 736  * adding in the last group in case things have changed since verifying.
 737  */
 738 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 739 {
 740         struct ext4_sb_info *sbi = EXT4_SB(sb);
 741         struct ext4_super_block *es = sbi->s_es;
 742         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
 743                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
 744         struct buffer_head *primary = NULL;
 745         struct ext4_group_desc *gdp;
 746         struct inode *inode = NULL;
 747         handle_t *handle;
 748         int gdb_off, gdb_num;
 749         int num_grp_locked = 0;
 750         int err, err2;
 751
 752         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
 753         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
 754
 755         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
 756                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 757                 ext4_warning(sb, __func__,
 758                              "Can't resize non-sparse filesystem further");
 759                 return -EPERM;
 760         }
 761
 762         if (ext4_blocks_count(es) + input->blocks_count <
 763             ext4_blocks_count(es)) {
 764                 ext4_warning(sb, __func__, "blocks_count overflow");
 765                 return -EINVAL;
 766         }
 767
 768         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
 769             le32_to_cpu(es->s_inodes_count)) {
 770                 ext4_warning(sb, __func__, "inodes_count overflow");
 771                 return -EINVAL;
 772         }
 773
 774         if (reserved_gdb || gdb_off == 0) {
 775                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
 776                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)
 777                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
 778                         ext4_warning(sb, __func__,
 779                                      "No reserved GDT blocks, can't resize");
 780                         return -EPERM;
 781                 }
 782                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
 783                 if (IS_ERR(inode)) {
 784                         ext4_warning(sb, __func__,
 785                                      "Error opening resize inode");
 786                         return PTR_ERR(inode);
 787                 }
 788         }
 789
 790
 791         if ((err = verify_group_input(sb, input)))
 792                 goto exit_put;
 793
 794         if ((err = setup_new_group_blocks(sb, input)))
 795                 goto exit_put;
 796
 797         /*
 798          * We will always be modifying at least the superblock and a GDT
 799          * block.  If we are adding a group past the last current GDT block,
 800          * we will also modify the inode and the dindirect block.  If we
 801          * are adding a group with superblock/GDT backups  we will also
 802          * modify each of the reserved GDT dindirect blocks.
 803          */
 804         handle = ext4_journal_start_sb(sb,
 805                                        ext4_bg_has_super(sb, input->group) ?
 806                                        3 + reserved_gdb : 4);
 807         if (IS_ERR(handle)) {
 808                 err = PTR_ERR(handle);
 809                 goto exit_put;
 810         }
 811
 812         mutex_lock(&sbi->s_resize_lock);
 813         if (input->group != sbi->s_groups_count) {
 814                 ext4_warning(sb, __func__,
 815                              "multiple resizers run on filesystem!");
 816                 err = -EBUSY;
 817                 goto exit_journal;
 818         }
 819
 820         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
 821                 goto exit_journal;
 822
 823         /*
 824          * We will only either add reserved group blocks to a backup group
 825          * or remove reserved blocks for the first group in a new group block.
 826          * Doing both would be mean more complex code, and sane people don't
 827          * use non-sparse filesystems anymore.  This is already checked above.
 828          */
 829         if (gdb_off) {
 830                 primary = sbi->s_group_desc[gdb_num];
 831                 if ((err = ext4_journal_get_write_access(handle, primary)))
 832                         goto exit_journal;
 833
 834                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
 835                     (err = reserve_backup_gdb(handle, inode, input)))
 836                         goto exit_journal;
 837         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
 838                 goto exit_journal;
 839
 840         /*
 841          * OK, now we've set up the new group.  Time to make it active.
 842          *
 843          * We do not lock all allocations via s_resize_lock
 844          * so we have to be safe wrt. concurrent accesses the group
 845          * data.  So we need to be careful to set all of the relevant
 846          * group descriptor data etc. *before* we enable the group.
 847          *
 848          * The key field here is sbi->s_groups_count: as long as
 849          * that retains its old value, nobody is going to access the new
 850          * group.
 851          *
 852          * So first we update all the descriptor metadata for the new
 853          * group; then we update the total disk blocks count; then we
 854          * update the groups count to enable the group; then finally we
 855          * update the free space counts so that the system can start
 856          * using the new disk blocks.
 857          */
 858
 859         num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group);
 860         /* Update group descriptor block for new group */
 861         gdp = (struct ext4_group_desc *)((char *)primary->b_data +
 862                                          gdb_off * EXT4_DESC_SIZE(sb));
 863
 864         memset(gdp, 0, EXT4_DESC_SIZE(sb));
 865         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
 866         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
 867         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
 868         ext4_free_blks_set(sb, gdp, input->free_blocks_count);
 869         ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
 870         gdp->bg_flags = cpu_to_le16(EXT4_BG_INODE_ZEROED);
 871         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
 872
 873         /*
 874          * We can allocate memory for mb_alloc based on the new group
 875          * descriptor
 876          */
 877         err = ext4_mb_add_groupinfo(sb, input->group, gdp);
 878         if (err) {
 879                 ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 880                 goto exit_journal;
 881         }
 882
 883         /*
 884          * Make the new blocks and inodes valid next.  We do this before
 885          * increasing the group count so that once the group is enabled,
 886          * all of its blocks and inodes are already valid.
 887          *
 888          * We always allocate group-by-group, then block-by-block or
 889          * inode-by-inode within a group, so enabling these
 890          * blocks/inodes before the group is live won't actually let us
 891          * allocate the new space yet.
 892          */
 893         ext4_blocks_count_set(es, ext4_blocks_count(es) +
 894                 input->blocks_count);
 895         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb));
 896
 897         /*
 898          * We need to protect s_groups_count against other CPUs seeing
 899          * inconsistent state in the superblock.
 900          *
 901          * The precise rules we use are:
 902          *
 903          * * Writers of s_groups_count *must* hold s_resize_lock
 904          * AND
 905          * * Writers must perform a smp_wmb() after updating all dependent
 906          *   data and before modifying the groups count
 907          *
 908          * * Readers must hold s_resize_lock over the access
 909          * OR
 910          * * Readers must perform an smp_rmb() after reading the groups count
 911          *   and before reading any dependent data.
 912          *
 913          * NB. These rules can be relaxed when checking the group count
 914          * while freeing data, as we can only allocate from a block
 915          * group after serialising against the group count, and we can
 916          * only then free after serialising in turn against that
 917          * allocation.
 918          */
 919         smp_wmb();
 920
 921         /* Update the global fs size fields */
 922         sbi->s_groups_count++;
 923         ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 924
 925         ext4_handle_dirty_metadata(handle, NULL, primary);
 926
 927         /* Update the reserved block counts only once the new group is
 928          * active. */
 929         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 930                 input->reserved_blocks);
 931
 932         /* Update the free space counts */
 933         percpu_counter_add(&sbi->s_freeblocks_counter,
 934                            input->free_blocks_count);
 935         percpu_counter_add(&sbi->s_freeinodes_counter,
 936                            EXT4_INODES_PER_GROUP(sb));
 937
 938         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 939                 ext4_group_t flex_group;
 940                 flex_group = ext4_flex_group(sbi, input->group);
 941                 atomic_add(input->free_blocks_count,
 942                            &sbi->s_flex_groups[flex_group].free_blocks);
 943                 atomic_add(EXT4_INODES_PER_GROUP(sb),
 944                            &sbi->s_flex_groups[flex_group].free_inodes);
 945         }
 946
 947         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 948         sb->s_dirt = 1;
 949
 950 exit_journal:
 951         mutex_unlock(&sbi->s_resize_lock);
 952         if ((err2 = ext4_journal_stop(handle)) && !err)
 953                 err = err2;
 954         if (!err) {
 955                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 956                                sizeof(struct ext4_super_block));
 957                 update_backups(sb, primary->b_blocknr, primary->b_data,
 958                                primary->b_size);
 959         }
 960 exit_put:
 961         iput(inode);
 962         return err;
 963 } /* ext4_group_add */
 964
 965 /*
 966  * Extend the filesystem to the new number of blocks specified.  This entry
 967  * point is only used to extend the current filesystem to the end of the last
 968  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
 969  * for emergencies (because it has no dependencies on reserved blocks).
 970  *
 971  * If we _really_ wanted, we could use default values to call ext4_group_add()
 972  * allow the "remount" trick to work for arbitrary resizing, assuming enough
 973  * GDT blocks are reserved to grow to the desired size.
 974  */
 975 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 976                       ext4_fsblk_t n_blocks_count)
 977 {
 978         ext4_fsblk_t o_blocks_count;
 979         ext4_group_t o_groups_count;
 980         ext4_grpblk_t last;
 981         ext4_grpblk_t add;
 982         struct buffer_head *bh;
 983         handle_t *handle;
 984         int err;
 985         ext4_group_t group;
 986
 987         /* We don't need to worry about locking wrt other resizers just
 988          * yet: we're going to revalidate es->s_blocks_count after
 989          * taking the s_resize_lock below. */
 990         o_blocks_count = ext4_blocks_count(es);
 991         o_groups_count = EXT4_SB(sb)->s_groups_count;
 992
 993         if (test_opt(sb, DEBUG))
 994                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
 995                        o_blocks_count, n_blocks_count);
 996
 997         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
 998                 return 0;
 999
1000         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1001                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
1002                         " too large to resize to %llu blocks safely\n",
1003                         sb->s_id, n_blocks_count);
1004                 if (sizeof(sector_t) < 8)
1005                         ext4_warning(sb, __func__, "CONFIG_LBDAF not enabled");
1006                 return -EINVAL;
1007         }
1008
1009         if (n_blocks_count < o_blocks_count) {
1010                 ext4_warning(sb, __func__,
1011                              "can't shrink FS - resize aborted");
1012                 return -EBUSY;
1013         }
1014
1015         /* Handle the remaining blocks in the last group only. */
1016         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1017
1018         if (last == 0) {
1019                 ext4_warning(sb, __func__,
1020                              "need to use ext2online to resize further");
1021                 return -EPERM;
1022         }
1023
1024         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1025
1026         if (o_blocks_count + add < o_blocks_count) {
1027                 ext4_warning(sb, __func__, "blocks_count overflow");
1028                 return -EINVAL;
1029         }
1030
1031         if (o_blocks_count + add > n_blocks_count)
1032                 add = n_blocks_count - o_blocks_count;
1033
1034         if (o_blocks_count + add < n_blocks_count)
1035                 ext4_warning(sb, __func__,
1036                              "will only finish group (%llu"
1037                              " blocks, %u new)",
1038                              o_blocks_count + add, add);
1039
1040         /* See if the device is actually as big as what was requested */
1041         bh = sb_bread(sb, o_blocks_count + add - 1);
1042         if (!bh) {
1043                 ext4_warning(sb, __func__,
1044                              "can't read last block, resize aborted");
1045                 return -ENOSPC;
1046         }
1047         brelse(bh);
1048
1049         /* We will update the superblock, one block bitmap, and
1050          * one group descriptor via ext4_free_blocks().
1051          */
1052         handle = ext4_journal_start_sb(sb, 3);
1053         if (IS_ERR(handle)) {
1054                 err = PTR_ERR(handle);
1055                 ext4_warning(sb, __func__, "error %d on journal start", err);
1056                 goto exit_put;
1057         }
1058
1059         mutex_lock(&EXT4_SB(sb)->s_resize_lock);
1060         if (o_blocks_count != ext4_blocks_count(es)) {
1061                 ext4_warning(sb, __func__,
1062                              "multiple resizers run on filesystem!");
1063                 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1064                 ext4_journal_stop(handle);
1065                 err = -EBUSY;
1066                 goto exit_put;
1067         }
1068
1069         if ((err = ext4_journal_get_write_access(handle,
1070                                                  EXT4_SB(sb)->s_sbh))) {
1071                 ext4_warning(sb, __func__,
1072                              "error %d on journal write access", err);
1073                 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1074                 ext4_journal_stop(handle);
1075                 goto exit_put;
1076         }
1077         ext4_blocks_count_set(es, o_blocks_count + add);
1078         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
1079         sb->s_dirt = 1;
1080         mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1081         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1082                    o_blocks_count + add);
1083         /* We add the blocks to the bitmap and set the group need init bit */
1084         ext4_add_groupblocks(handle, sb, o_blocks_count, add);
1085         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1086                    o_blocks_count + add);
1087         if ((err = ext4_journal_stop(handle)))
1088                 goto exit_put;
1089
1090         if (test_opt(sb, DEBUG))
1091                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1092                        ext4_blocks_count(es));
1093         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1094                        sizeof(struct ext4_super_block));
1095 exit_put:
1096         return err;
1097 } /* ext4_group_extend */