fs/ext4/resize.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/resize.c
   4  *
   5  * Support for resizing an ext4 filesystem while it is mounted.
   6  *
   7  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
   8  *
   9  * This could probably be made into a module, because it is not often in use.
  10  */
  11
  12
  13 #define EXT4FS_DEBUG
  14
  15 #include <linux/errno.h>
  16 #include <linux/slab.h>
  17
  18 #include "ext4_jbd2.h"
  19
  20 int ext4_resize_begin(struct super_block *sb)
  21 {
  22         struct ext4_sb_info *sbi = EXT4_SB(sb);
  23         int ret = 0;
  24
  25         if (!capable(CAP_SYS_RESOURCE))
  26                 return -EPERM;
  27
  28         /*
  29          * If we are not using the primary superblock/GDT copy don't resize,
  30          * because the user tools have no way of handling this.  Probably a
  31          * bad time to do it anyways.
  32          */
  33         if (EXT4_B2C(sbi, sbi->s_sbh->b_blocknr) !=
  34             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
  35                 ext4_warning(sb, "won't resize using backup superblock at %llu",
  36                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
  37                 return -EPERM;
  38         }
  39
  40         /*
  41          * We are not allowed to do online-resizing on a filesystem mounted
  42          * with error, because it can destroy the filesystem easily.
  43          */
  44         if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
  45                 ext4_warning(sb, "There are errors in the filesystem, "
  46                              "so online resizing is not allowed");
  47                 return -EPERM;
  48         }
  49
  50         if (test_and_set_bit_lock(EXT4_FLAGS_RESIZING,
  51                                   &EXT4_SB(sb)->s_ext4_flags))
  52                 ret = -EBUSY;
  53
  54         return ret;
  55 }
  56
  57 void ext4_resize_end(struct super_block *sb)
  58 {
  59         clear_bit_unlock(EXT4_FLAGS_RESIZING, &EXT4_SB(sb)->s_ext4_flags);
  60         smp_mb__after_atomic();
  61 }
  62
  63 static ext4_group_t ext4_meta_bg_first_group(struct super_block *sb,
  64                                              ext4_group_t group) {
  65         return (group >> EXT4_DESC_PER_BLOCK_BITS(sb)) <<
  66                EXT4_DESC_PER_BLOCK_BITS(sb);
  67 }
  68
  69 static ext4_fsblk_t ext4_meta_bg_first_block_no(struct super_block *sb,
  70                                              ext4_group_t group) {
  71         group = ext4_meta_bg_first_group(sb, group);
  72         return ext4_group_first_block_no(sb, group);
  73 }
  74
  75 static ext4_grpblk_t ext4_group_overhead_blocks(struct super_block *sb,
  76                                                 ext4_group_t group) {
  77         ext4_grpblk_t overhead;
  78         overhead = ext4_bg_num_gdb(sb, group);
  79         if (ext4_bg_has_super(sb, group))
  80                 overhead += 1 +
  81                           le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
  82         return overhead;
  83 }
  84
  85 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  86 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  87
  88 static int verify_group_input(struct super_block *sb,
  89                               struct ext4_new_group_data *input)
  90 {
  91         struct ext4_sb_info *sbi = EXT4_SB(sb);
  92         struct ext4_super_block *es = sbi->s_es;
  93         ext4_fsblk_t start = ext4_blocks_count(es);
  94         ext4_fsblk_t end = start + input->blocks_count;
  95         ext4_group_t group = input->group;
  96         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  97         unsigned overhead;
  98         ext4_fsblk_t metaend;
  99         struct buffer_head *bh = NULL;
 100         ext4_grpblk_t free_blocks_count, offset;
 101         int err = -EINVAL;
 102
 103         if (group != sbi->s_groups_count) {
 104                 ext4_warning(sb, "Cannot add at group %u (only %u groups)",
 105                              input->group, sbi->s_groups_count);
 106                 return -EINVAL;
 107         }
 108
 109         overhead = ext4_group_overhead_blocks(sb, group);
 110         metaend = start + overhead;
 111         input->free_clusters_count = free_blocks_count =
 112                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
 113
 114         if (test_opt(sb, DEBUG))
 115                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
 116                        "(%d free, %u reserved)\n",
 117                        ext4_bg_has_super(sb, input->group) ? "normal" :
 118                        "no-super", input->group, input->blocks_count,
 119                        free_blocks_count, input->reserved_blocks);
 120
 121         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
 122         if (offset != 0)
 123                         ext4_warning(sb, "Last group not full");
 124         else if (input->reserved_blocks > input->blocks_count / 5)
 125                 ext4_warning(sb, "Reserved blocks too high (%u)",
 126                              input->reserved_blocks);
 127         else if (free_blocks_count < 0)
 128                 ext4_warning(sb, "Bad blocks count %u",
 129                              input->blocks_count);
 130         else if (IS_ERR(bh = ext4_sb_bread(sb, end - 1, 0))) {
 131                 err = PTR_ERR(bh);
 132                 bh = NULL;
 133                 ext4_warning(sb, "Cannot read last block (%llu)",
 134                              end - 1);
 135         } else if (outside(input->block_bitmap, start, end))
 136                 ext4_warning(sb, "Block bitmap not in group (block %llu)",
 137                              (unsigned long long)input->block_bitmap);
 138         else if (outside(input->inode_bitmap, start, end))
 139                 ext4_warning(sb, "Inode bitmap not in group (block %llu)",
 140                              (unsigned long long)input->inode_bitmap);
 141         else if (outside(input->inode_table, start, end) ||
 142                  outside(itend - 1, start, end))
 143                 ext4_warning(sb, "Inode table not in group (blocks %llu-%llu)",
 144                              (unsigned long long)input->inode_table, itend - 1);
 145         else if (input->inode_bitmap == input->block_bitmap)
 146                 ext4_warning(sb, "Block bitmap same as inode bitmap (%llu)",
 147                              (unsigned long long)input->block_bitmap);
 148         else if (inside(input->block_bitmap, input->inode_table, itend))
 149                 ext4_warning(sb, "Block bitmap (%llu) in inode table "
 150                              "(%llu-%llu)",
 151                              (unsigned long long)input->block_bitmap,
 152                              (unsigned long long)input->inode_table, itend - 1);
 153         else if (inside(input->inode_bitmap, input->inode_table, itend))
 154                 ext4_warning(sb, "Inode bitmap (%llu) in inode table "
 155                              "(%llu-%llu)",
 156                              (unsigned long long)input->inode_bitmap,
 157                              (unsigned long long)input->inode_table, itend - 1);
 158         else if (inside(input->block_bitmap, start, metaend))
 159                 ext4_warning(sb, "Block bitmap (%llu) in GDT table (%llu-%llu)",
 160                              (unsigned long long)input->block_bitmap,
 161                              start, metaend - 1);
 162         else if (inside(input->inode_bitmap, start, metaend))
 163                 ext4_warning(sb, "Inode bitmap (%llu) in GDT table (%llu-%llu)",
 164                              (unsigned long long)input->inode_bitmap,
 165                              start, metaend - 1);
 166         else if (inside(input->inode_table, start, metaend) ||
 167                  inside(itend - 1, start, metaend))
 168                 ext4_warning(sb, "Inode table (%llu-%llu) overlaps GDT table "
 169                              "(%llu-%llu)",
 170                              (unsigned long long)input->inode_table,
 171                              itend - 1, start, metaend - 1);
 172         else
 173                 err = 0;
 174         brelse(bh);
 175
 176         return err;
 177 }
 178
 179 /*
 180  * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
 181  * group each time.
 182  */
 183 struct ext4_new_flex_group_data {
 184         struct ext4_new_group_data *groups;     /* new_group_data for groups
 185                                                    in the flex group */
 186         __u16 *bg_flags;                        /* block group flags of groups
 187                                                    in @groups */
 188         ext4_group_t count;                     /* number of groups in @groups
 189                                                  */
 190 };
 191
 192 /*
 193  * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
 194  * @flexbg_size.
 195  *
 196  * Returns NULL on failure otherwise address of the allocated structure.
 197  */
 198 static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
 199 {
 200         struct ext4_new_flex_group_data *flex_gd;
 201
 202         flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
 203         if (flex_gd == NULL)
 204                 goto out3;
 205
 206         if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_group_data))
 207                 goto out2;
 208         flex_gd->count = flexbg_size;
 209
 210         flex_gd->groups = kmalloc_array(flexbg_size,
 211                                         sizeof(struct ext4_new_group_data),
 212                                         GFP_NOFS);
 213         if (flex_gd->groups == NULL)
 214                 goto out2;
 215
 216         flex_gd->bg_flags = kmalloc_array(flexbg_size, sizeof(__u16),
 217                                           GFP_NOFS);
 218         if (flex_gd->bg_flags == NULL)
 219                 goto out1;
 220
 221         return flex_gd;
 222
 223 out1:
 224         kfree(flex_gd->groups);
 225 out2:
 226         kfree(flex_gd);
 227 out3:
 228         return NULL;
 229 }
 230
 231 static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
 232 {
 233         kfree(flex_gd->bg_flags);
 234         kfree(flex_gd->groups);
 235         kfree(flex_gd);
 236 }
 237
 238 /*
 239  * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
 240  * and inode tables for a flex group.
 241  *
 242  * This function is used by 64bit-resize.  Note that this function allocates
 243  * group tables from the 1st group of groups contained by @flexgd, which may
 244  * be a partial of a flex group.
 245  *
 246  * @sb: super block of fs to which the groups belongs
 247  *
 248  * Returns 0 on a successful allocation of the metadata blocks in the
 249  * block group.
 250  */
 251 static int ext4_alloc_group_tables(struct super_block *sb,
 252                                 struct ext4_new_flex_group_data *flex_gd,
 253                                 int flexbg_size)
 254 {
 255         struct ext4_new_group_data *group_data = flex_gd->groups;
 256         ext4_fsblk_t start_blk;
 257         ext4_fsblk_t last_blk;
 258         ext4_group_t src_group;
 259         ext4_group_t bb_index = 0;
 260         ext4_group_t ib_index = 0;
 261         ext4_group_t it_index = 0;
 262         ext4_group_t group;
 263         ext4_group_t last_group;
 264         unsigned overhead;
 265         __u16 uninit_mask = (flexbg_size > 1) ? ~EXT4_BG_BLOCK_UNINIT : ~0;
 266         int i;
 267
 268         BUG_ON(flex_gd->count == 0 || group_data == NULL);
 269
 270         src_group = group_data[0].group;
 271         last_group  = src_group + flex_gd->count - 1;
 272
 273         BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
 274                (last_group & ~(flexbg_size - 1))));
 275 next_group:
 276         group = group_data[0].group;
 277         if (src_group >= group_data[0].group + flex_gd->count)
 278                 return -ENOSPC;
 279         start_blk = ext4_group_first_block_no(sb, src_group);
 280         last_blk = start_blk + group_data[src_group - group].blocks_count;
 281
 282         overhead = ext4_group_overhead_blocks(sb, src_group);
 283
 284         start_blk += overhead;
 285
 286         /* We collect contiguous blocks as much as possible. */
 287         src_group++;
 288         for (; src_group <= last_group; src_group++) {
 289                 overhead = ext4_group_overhead_blocks(sb, src_group);
 290                 if (overhead == 0)
 291                         last_blk += group_data[src_group - group].blocks_count;
 292                 else
 293                         break;
 294         }
 295
 296         /* Allocate block bitmaps */
 297         for (; bb_index < flex_gd->count; bb_index++) {
 298                 if (start_blk >= last_blk)
 299                         goto next_group;
 300                 group_data[bb_index].block_bitmap = start_blk++;
 301                 group = ext4_get_group_number(sb, start_blk - 1);
 302                 group -= group_data[0].group;
 303                 group_data[group].mdata_blocks++;
 304                 flex_gd->bg_flags[group] &= uninit_mask;
 305         }
 306
 307         /* Allocate inode bitmaps */
 308         for (; ib_index < flex_gd->count; ib_index++) {
 309                 if (start_blk >= last_blk)
 310                         goto next_group;
 311                 group_data[ib_index].inode_bitmap = start_blk++;
 312                 group = ext4_get_group_number(sb, start_blk - 1);
 313                 group -= group_data[0].group;
 314                 group_data[group].mdata_blocks++;
 315                 flex_gd->bg_flags[group] &= uninit_mask;
 316         }
 317
 318         /* Allocate inode tables */
 319         for (; it_index < flex_gd->count; it_index++) {
 320                 unsigned int itb = EXT4_SB(sb)->s_itb_per_group;
 321                 ext4_fsblk_t next_group_start;
 322
 323                 if (start_blk + itb > last_blk)
 324                         goto next_group;
 325                 group_data[it_index].inode_table = start_blk;
 326                 group = ext4_get_group_number(sb, start_blk);
 327                 next_group_start = ext4_group_first_block_no(sb, group + 1);
 328                 group -= group_data[0].group;
 329
 330                 if (start_blk + itb > next_group_start) {
 331                         flex_gd->bg_flags[group + 1] &= uninit_mask;
 332                         overhead = start_blk + itb - next_group_start;
 333                         group_data[group + 1].mdata_blocks += overhead;
 334                         itb -= overhead;
 335                 }
 336
 337                 group_data[group].mdata_blocks += itb;
 338                 flex_gd->bg_flags[group] &= uninit_mask;
 339                 start_blk += EXT4_SB(sb)->s_itb_per_group;
 340         }
 341
 342         /* Update free clusters count to exclude metadata blocks */
 343         for (i = 0; i < flex_gd->count; i++) {
 344                 group_data[i].free_clusters_count -=
 345                                 EXT4_NUM_B2C(EXT4_SB(sb),
 346                                              group_data[i].mdata_blocks);
 347         }
 348
 349         if (test_opt(sb, DEBUG)) {
 350                 int i;
 351                 group = group_data[0].group;
 352
 353                 printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
 354                        "%d groups, flexbg size is %d:\n", flex_gd->count,
 355                        flexbg_size);
 356
 357                 for (i = 0; i < flex_gd->count; i++) {
 358                         ext4_debug(
 359                                "adding %s group %u: %u blocks (%d free, %d mdata blocks)\n",
 360                                ext4_bg_has_super(sb, group + i) ? "normal" :
 361                                "no-super", group + i,
 362                                group_data[i].blocks_count,
 363                                group_data[i].free_clusters_count,
 364                                group_data[i].mdata_blocks);
 365                 }
 366         }
 367         return 0;
 368 }
 369
 370 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 371                                   ext4_fsblk_t blk)
 372 {
 373         struct buffer_head *bh;
 374         int err;
 375
 376         bh = sb_getblk(sb, blk);
 377         if (unlikely(!bh))
 378                 return ERR_PTR(-ENOMEM);
 379         BUFFER_TRACE(bh, "get_write_access");
 380         if ((err = ext4_journal_get_write_access(handle, bh))) {
 381                 brelse(bh);
 382                 bh = ERR_PTR(err);
 383         } else {
 384                 memset(bh->b_data, 0, sb->s_blocksize);
 385                 set_buffer_uptodate(bh);
 386         }
 387
 388         return bh;
 389 }
 390
 391 /*
 392  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 393  * If that fails, restart the transaction & regain write access for the
 394  * buffer head which is used for block_bitmap modifications.
 395  */
 396 static int extend_or_restart_transaction(handle_t *handle, int thresh)
 397 {
 398         int err;
 399
 400         if (ext4_handle_has_enough_credits(handle, thresh))
 401                 return 0;
 402
 403         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 404         if (err < 0)
 405                 return err;
 406         if (err) {
 407                 err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA);
 408                 if (err)
 409                         return err;
 410         }
 411
 412         return 0;
 413 }
 414
 415 /*
 416  * set_flexbg_block_bitmap() mark clusters [@first_cluster, @last_cluster] used.
 417  *
 418  * Helper function for ext4_setup_new_group_blocks() which set .
 419  *
 420  * @sb: super block
 421  * @handle: journal handle
 422  * @flex_gd: flex group data
 423  */
 424 static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 425                         struct ext4_new_flex_group_data *flex_gd,
 426                         ext4_fsblk_t first_cluster, ext4_fsblk_t last_cluster)
 427 {
 428         struct ext4_sb_info *sbi = EXT4_SB(sb);
 429         ext4_group_t count = last_cluster - first_cluster + 1;
 430         ext4_group_t count2;
 431
 432         ext4_debug("mark clusters [%llu-%llu] used\n", first_cluster,
 433                    last_cluster);
 434         for (count2 = count; count > 0;
 435              count -= count2, first_cluster += count2) {
 436                 ext4_fsblk_t start;
 437                 struct buffer_head *bh;
 438                 ext4_group_t group;
 439                 int err;
 440
 441                 group = ext4_get_group_number(sb, EXT4_C2B(sbi, first_cluster));
 442                 start = EXT4_B2C(sbi, ext4_group_first_block_no(sb, group));
 443                 group -= flex_gd->groups[0].group;
 444
 445                 count2 = EXT4_CLUSTERS_PER_GROUP(sb) - (first_cluster - start);
 446                 if (count2 > count)
 447                         count2 = count;
 448
 449                 if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
 450                         BUG_ON(flex_gd->count > 1);
 451                         continue;
 452                 }
 453
 454                 err = extend_or_restart_transaction(handle, 1);
 455                 if (err)
 456                         return err;
 457
 458                 bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
 459                 if (unlikely(!bh))
 460                         return -ENOMEM;
 461
 462                 BUFFER_TRACE(bh, "get_write_access");
 463                 err = ext4_journal_get_write_access(handle, bh);
 464                 if (err) {
 465                         brelse(bh);
 466                         return err;
 467                 }
 468                 ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n",
 469                            first_cluster, first_cluster - start, count2);
 470                 ext4_set_bits(bh->b_data, first_cluster - start, count2);
 471
 472                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 473                 brelse(bh);
 474                 if (unlikely(err))
 475                         return err;
 476         }
 477
 478         return 0;
 479 }
 480
 481 /*
 482  * Set up the block and inode bitmaps, and the inode table for the new groups.
 483  * This doesn't need to be part of the main transaction, since we are only
 484  * changing blocks outside the actual filesystem.  We still do journaling to
 485  * ensure the recovery is correct in case of a failure just after resize.
 486  * If any part of this fails, we simply abort the resize.
 487  *
 488  * setup_new_flex_group_blocks handles a flex group as follow:
 489  *  1. copy super block and GDT, and initialize group tables if necessary.
 490  *     In this step, we only set bits in blocks bitmaps for blocks taken by
 491  *     super block and GDT.
 492  *  2. allocate group tables in block bitmaps, that is, set bits in block
 493  *     bitmap for blocks taken by group tables.
 494  */
 495 static int setup_new_flex_group_blocks(struct super_block *sb,
 496                                 struct ext4_new_flex_group_data *flex_gd)
 497 {
 498         int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
 499         ext4_fsblk_t start;
 500         ext4_fsblk_t block;
 501         struct ext4_sb_info *sbi = EXT4_SB(sb);
 502         struct ext4_super_block *es = sbi->s_es;
 503         struct ext4_new_group_data *group_data = flex_gd->groups;
 504         __u16 *bg_flags = flex_gd->bg_flags;
 505         handle_t *handle;
 506         ext4_group_t group, count;
 507         struct buffer_head *bh = NULL;
 508         int reserved_gdb, i, j, err = 0, err2;
 509         int meta_bg;
 510
 511         BUG_ON(!flex_gd->count || !group_data ||
 512                group_data[0].group != sbi->s_groups_count);
 513
 514         reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
 515         meta_bg = ext4_has_feature_meta_bg(sb);
 516
 517         /* This transaction may be extended/restarted along the way */
 518         handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
 519         if (IS_ERR(handle))
 520                 return PTR_ERR(handle);
 521
 522         group = group_data[0].group;
 523         for (i = 0; i < flex_gd->count; i++, group++) {
 524                 unsigned long gdblocks;
 525                 ext4_grpblk_t overhead;
 526
 527                 gdblocks = ext4_bg_num_gdb(sb, group);
 528                 start = ext4_group_first_block_no(sb, group);
 529
 530                 if (meta_bg == 0 && !ext4_bg_has_super(sb, group))
 531                         goto handle_itb;
 532
 533                 if (meta_bg == 1) {
 534                         ext4_group_t first_group;
 535                         first_group = ext4_meta_bg_first_group(sb, group);
 536                         if (first_group != group + 1 &&
 537                             first_group != group + EXT4_DESC_PER_BLOCK(sb) - 1)
 538                                 goto handle_itb;
 539                 }
 540
 541                 block = start + ext4_bg_has_super(sb, group);
 542                 /* Copy all of the GDT blocks into the backup in this group */
 543                 for (j = 0; j < gdblocks; j++, block++) {
 544                         struct buffer_head *gdb;
 545
 546                         ext4_debug("update backup group %#04llx\n", block);
 547                         err = extend_or_restart_transaction(handle, 1);
 548                         if (err)
 549                                 goto out;
 550
 551                         gdb = sb_getblk(sb, block);
 552                         if (unlikely(!gdb)) {
 553                                 err = -ENOMEM;
 554                                 goto out;
 555                         }
 556
 557                         BUFFER_TRACE(gdb, "get_write_access");
 558                         err = ext4_journal_get_write_access(handle, gdb);
 559                         if (err) {
 560                                 brelse(gdb);
 561                                 goto out;
 562                         }
 563                         memcpy(gdb->b_data, sbi->s_group_desc[j]->b_data,
 564                                gdb->b_size);
 565                         set_buffer_uptodate(gdb);
 566
 567                         err = ext4_handle_dirty_metadata(handle, NULL, gdb);
 568                         if (unlikely(err)) {
 569                                 brelse(gdb);
 570                                 goto out;
 571                         }
 572                         brelse(gdb);
 573                 }
 574
 575                 /* Zero out all of the reserved backup group descriptor
 576                  * table blocks
 577                  */
 578                 if (ext4_bg_has_super(sb, group)) {
 579                         err = sb_issue_zeroout(sb, gdblocks + start + 1,
 580                                         reserved_gdb, GFP_NOFS);
 581                         if (err)
 582                                 goto out;
 583                 }
 584
 585 handle_itb:
 586                 /* Initialize group tables of the grop @group */
 587                 if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
 588                         goto handle_bb;
 589
 590                 /* Zero out all of the inode table blocks */
 591                 block = group_data[i].inode_table;
 592                 ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
 593                            block, sbi->s_itb_per_group);
 594                 err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
 595                                        GFP_NOFS);
 596                 if (err)
 597                         goto out;
 598
 599 handle_bb:
 600                 if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
 601                         goto handle_ib;
 602
 603                 /* Initialize block bitmap of the @group */
 604                 block = group_data[i].block_bitmap;
 605                 err = extend_or_restart_transaction(handle, 1);
 606                 if (err)
 607                         goto out;
 608
 609                 bh = bclean(handle, sb, block);
 610                 if (IS_ERR(bh)) {
 611                         err = PTR_ERR(bh);
 612                         goto out;
 613                 }
 614                 overhead = ext4_group_overhead_blocks(sb, group);
 615                 if (overhead != 0) {
 616                         ext4_debug("mark backup superblock %#04llx (+0)\n",
 617                                    start);
 618                         ext4_set_bits(bh->b_data, 0,
 619                                       EXT4_NUM_B2C(sbi, overhead));
 620                 }
 621                 ext4_mark_bitmap_end(EXT4_B2C(sbi, group_data[i].blocks_count),
 622                                      sb->s_blocksize * 8, bh->b_data);
 623                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 624                 brelse(bh);
 625                 if (err)
 626                         goto out;
 627
 628 handle_ib:
 629                 if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
 630                         continue;
 631
 632                 /* Initialize inode bitmap of the @group */
 633                 block = group_data[i].inode_bitmap;
 634                 err = extend_or_restart_transaction(handle, 1);
 635                 if (err)
 636                         goto out;
 637                 /* Mark unused entries in inode bitmap used */
 638                 bh = bclean(handle, sb, block);
 639                 if (IS_ERR(bh)) {
 640                         err = PTR_ERR(bh);
 641                         goto out;
 642                 }
 643
 644                 ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
 645                                      sb->s_blocksize * 8, bh->b_data);
 646                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 647                 brelse(bh);
 648                 if (err)
 649                         goto out;
 650         }
 651
 652         /* Mark group tables in block bitmap */
 653         for (j = 0; j < GROUP_TABLE_COUNT; j++) {
 654                 count = group_table_count[j];
 655                 start = (&group_data[0].block_bitmap)[j];
 656                 block = start;
 657                 for (i = 1; i < flex_gd->count; i++) {
 658                         block += group_table_count[j];
 659                         if (block == (&group_data[i].block_bitmap)[j]) {
 660                                 count += group_table_count[j];
 661                                 continue;
 662                         }
 663                         err = set_flexbg_block_bitmap(sb, handle,
 664                                                       flex_gd,
 665                                                       EXT4_B2C(sbi, start),
 666                                                       EXT4_B2C(sbi,
 667                                                                start + count
 668                                                                - 1));
 669                         if (err)
 670                                 goto out;
 671                         count = group_table_count[j];
 672                         start = (&group_data[i].block_bitmap)[j];
 673                         block = start;
 674                 }
 675
 676                 if (count) {
 677                         err = set_flexbg_block_bitmap(sb, handle,
 678                                                       flex_gd,
 679                                                       EXT4_B2C(sbi, start),
 680                                                       EXT4_B2C(sbi,
 681                                                                start + count
 682                                                                - 1));
 683                         if (err)
 684                                 goto out;
 685                 }
 686         }
 687
 688 out:
 689         err2 = ext4_journal_stop(handle);
 690         if (err2 && !err)
 691                 err = err2;
 692
 693         return err;
 694 }
 695
 696 /*
 697  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 698  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 699  * calling this for the first time.  In a sparse filesystem it will be the
 700  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 701  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 702  */
 703 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 704                                   unsigned *five, unsigned *seven)
 705 {
 706         unsigned *min = three;
 707         int mult = 3;
 708         unsigned ret;
 709
 710         if (!ext4_has_feature_sparse_super(sb)) {
 711                 ret = *min;
 712                 *min += 1;
 713                 return ret;
 714         }
 715
 716         if (*five < *min) {
 717                 min = five;
 718                 mult = 5;
 719         }
 720         if (*seven < *min) {
 721                 min = seven;
 722                 mult = 7;
 723         }
 724
 725         ret = *min;
 726         *min *= mult;
 727
 728         return ret;
 729 }
 730
 731 /*
 732  * Check that all of the backup GDT blocks are held in the primary GDT block.
 733  * It is assumed that they are stored in group order.  Returns the number of
 734  * groups in current filesystem that have BACKUPS, or -ve error code.
 735  */
 736 static int verify_reserved_gdb(struct super_block *sb,
 737                                ext4_group_t end,
 738                                struct buffer_head *primary)
 739 {
 740         const ext4_fsblk_t blk = primary->b_blocknr;
 741         unsigned three = 1;
 742         unsigned five = 5;
 743         unsigned seven = 7;
 744         unsigned grp;
 745         __le32 *p = (__le32 *)primary->b_data;
 746         int gdbackups = 0;
 747
 748         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 749                 if (le32_to_cpu(*p++) !=
 750                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 751                         ext4_warning(sb, "reserved GDT %llu"
 752                                      " missing grp %d (%llu)",
 753                                      blk, grp,
 754                                      grp *
 755                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 756                                      blk);
 757                         return -EINVAL;
 758                 }
 759                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 760                         return -EFBIG;
 761         }
 762
 763         return gdbackups;
 764 }
 765
 766 /*
 767  * Called when we need to bring a reserved group descriptor table block into
 768  * use from the resize inode.  The primary copy of the new GDT block currently
 769  * is an indirect block (under the double indirect block in the resize inode).
 770  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 771  * block, in group order.  Even though we know all the block numbers we need,
 772  * we check to ensure that the resize inode has actually reserved these blocks.
 773  *
 774  * Don't need to update the block bitmaps because the blocks are still in use.
 775  *
 776  * We get all of the error cases out of the way, so that we are sure to not
 777  * fail once we start modifying the data on disk, because JBD has no rollback.
 778  */
 779 static int add_new_gdb(handle_t *handle, struct inode *inode,
 780                        ext4_group_t group)
 781 {
 782         struct super_block *sb = inode->i_sb;
 783         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 784         unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 785         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 786         struct buffer_head **o_group_desc, **n_group_desc = NULL;
 787         struct buffer_head *dind = NULL;
 788         struct buffer_head *gdb_bh = NULL;
 789         int gdbackups;
 790         struct ext4_iloc iloc = { .bh = NULL };
 791         __le32 *data;
 792         int err;
 793
 794         if (test_opt(sb, DEBUG))
 795                 printk(KERN_DEBUG
 796                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 797                        gdb_num);
 798
 799         gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 800         if (IS_ERR(gdb_bh))
 801                 return PTR_ERR(gdb_bh);
 802
 803         gdbackups = verify_reserved_gdb(sb, group, gdb_bh);
 804         if (gdbackups < 0) {
 805                 err = gdbackups;
 806                 goto errout;
 807         }
 808
 809         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 810         dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
 811         if (IS_ERR(dind)) {
 812                 err = PTR_ERR(dind);
 813                 dind = NULL;
 814                 goto errout;
 815         }
 816
 817         data = (__le32 *)dind->b_data;
 818         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 819                 ext4_warning(sb, "new group %u GDT block %llu not reserved",
 820                              group, gdblock);
 821                 err = -EINVAL;
 822                 goto errout;
 823         }
 824
 825         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 826         err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
 827         if (unlikely(err))
 828                 goto errout;
 829
 830         BUFFER_TRACE(gdb_bh, "get_write_access");
 831         err = ext4_journal_get_write_access(handle, gdb_bh);
 832         if (unlikely(err))
 833                 goto errout;
 834
 835         BUFFER_TRACE(dind, "get_write_access");
 836         err = ext4_journal_get_write_access(handle, dind);
 837         if (unlikely(err))
 838                 ext4_std_error(sb, err);
 839
 840         /* ext4_reserve_inode_write() gets a reference on the iloc */
 841         err = ext4_reserve_inode_write(handle, inode, &iloc);
 842         if (unlikely(err))
 843                 goto errout;
 844
 845         n_group_desc = ext4_kvmalloc((gdb_num + 1) *
 846                                      sizeof(struct buffer_head *),
 847                                      GFP_NOFS);
 848         if (!n_group_desc) {
 849                 err = -ENOMEM;
 850                 ext4_warning(sb, "not enough memory for %lu groups",
 851                              gdb_num + 1);
 852                 goto errout;
 853         }
 854
 855         /*
 856          * Finally, we have all of the possible failures behind us...
 857          *
 858          * Remove new GDT block from inode double-indirect block and clear out
 859          * the new GDT block for use (which also "frees" the backup GDT blocks
 860          * from the reserved inode).  We don't need to change the bitmaps for
 861          * these blocks, because they are marked as in-use from being in the
 862          * reserved inode, and will become GDT blocks (primary and backup).
 863          */
 864         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 865         err = ext4_handle_dirty_metadata(handle, NULL, dind);
 866         if (unlikely(err)) {
 867                 ext4_std_error(sb, err);
 868                 goto errout;
 869         }
 870         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >>
 871                            (9 - EXT4_SB(sb)->s_cluster_bits);
 872         ext4_mark_iloc_dirty(handle, inode, &iloc);
 873         memset(gdb_bh->b_data, 0, sb->s_blocksize);
 874         err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
 875         if (unlikely(err)) {
 876                 ext4_std_error(sb, err);
 877                 goto errout;
 878         }
 879         brelse(dind);
 880
 881         o_group_desc = EXT4_SB(sb)->s_group_desc;
 882         memcpy(n_group_desc, o_group_desc,
 883                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 884         n_group_desc[gdb_num] = gdb_bh;
 885         EXT4_SB(sb)->s_group_desc = n_group_desc;
 886         EXT4_SB(sb)->s_gdb_count++;
 887         kvfree(o_group_desc);
 888
 889         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 890         err = ext4_handle_dirty_super(handle, sb);
 891         if (err)
 892                 ext4_std_error(sb, err);
 893         return err;
 894 errout:
 895         kvfree(n_group_desc);
 896         brelse(iloc.bh);
 897         brelse(dind);
 898         brelse(gdb_bh);
 899
 900         ext4_debug("leaving with error %d\n", err);
 901         return err;
 902 }
 903
 904 /*
 905  * add_new_gdb_meta_bg is the sister of add_new_gdb.
 906  */
 907 static int add_new_gdb_meta_bg(struct super_block *sb,
 908                                handle_t *handle, ext4_group_t group) {
 909         ext4_fsblk_t gdblock;
 910         struct buffer_head *gdb_bh;
 911         struct buffer_head **o_group_desc, **n_group_desc;
 912         unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 913         int err;
 914
 915         gdblock = ext4_meta_bg_first_block_no(sb, group) +
 916                    ext4_bg_has_super(sb, group);
 917         gdb_bh = ext4_sb_bread(sb, gdblock, 0);
 918         if (IS_ERR(gdb_bh))
 919                 return PTR_ERR(gdb_bh);
 920         n_group_desc = ext4_kvmalloc((gdb_num + 1) *
 921                                      sizeof(struct buffer_head *),
 922                                      GFP_NOFS);
 923         if (!n_group_desc) {
 924                 brelse(gdb_bh);
 925                 err = -ENOMEM;
 926                 ext4_warning(sb, "not enough memory for %lu groups",
 927                              gdb_num + 1);
 928                 return err;
 929         }
 930
 931         o_group_desc = EXT4_SB(sb)->s_group_desc;
 932         memcpy(n_group_desc, o_group_desc,
 933                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 934         n_group_desc[gdb_num] = gdb_bh;
 935         EXT4_SB(sb)->s_group_desc = n_group_desc;
 936         EXT4_SB(sb)->s_gdb_count++;
 937         kvfree(o_group_desc);
 938         BUFFER_TRACE(gdb_bh, "get_write_access");
 939         err = ext4_journal_get_write_access(handle, gdb_bh);
 940         return err;
 941 }
 942
 943 /*
 944  * Called when we are adding a new group which has a backup copy of each of
 945  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 946  * We need to add these reserved backup GDT blocks to the resize inode, so
 947  * that they are kept for future resizing and not allocated to files.
 948  *
 949  * Each reserved backup GDT block will go into a different indirect block.
 950  * The indirect blocks are actually the primary reserved GDT blocks,
 951  * so we know in advance what their block numbers are.  We only get the
 952  * double-indirect block to verify it is pointing to the primary reserved
 953  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 954  * backup GDT blocks are stored in their reserved primary GDT block.
 955  */
 956 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 957                               ext4_group_t group)
 958 {
 959         struct super_block *sb = inode->i_sb;
 960         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 961         int cluster_bits = EXT4_SB(sb)->s_cluster_bits;
 962         struct buffer_head **primary;
 963         struct buffer_head *dind;
 964         struct ext4_iloc iloc;
 965         ext4_fsblk_t blk;
 966         __le32 *data, *end;
 967         int gdbackups = 0;
 968         int res, i;
 969         int err;
 970
 971         primary = kmalloc_array(reserved_gdb, sizeof(*primary), GFP_NOFS);
 972         if (!primary)
 973                 return -ENOMEM;
 974
 975         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 976         dind = ext4_sb_bread(sb, le32_to_cpu(*data), 0);
 977         if (IS_ERR(dind)) {
 978                 err = PTR_ERR(dind);
 979                 dind = NULL;
 980                 goto exit_free;
 981         }
 982
 983         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 984         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 985                                          EXT4_ADDR_PER_BLOCK(sb));
 986         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 987
 988         /* Get each reserved primary GDT block and verify it holds backups */
 989         for (res = 0; res < reserved_gdb; res++, blk++) {
 990                 if (le32_to_cpu(*data) != blk) {
 991                         ext4_warning(sb, "reserved block %llu"
 992                                      " not at offset %ld",
 993                                      blk,
 994                                      (long)(data - (__le32 *)dind->b_data));
 995                         err = -EINVAL;
 996                         goto exit_bh;
 997                 }
 998                 primary[res] = ext4_sb_bread(sb, blk, 0);
 999                 if (IS_ERR(primary[res])) {
1000                         err = PTR_ERR(primary[res]);
1001                         primary[res] = NULL;
1002                         goto exit_bh;
1003                 }
1004                 gdbackups = verify_reserved_gdb(sb, group, primary[res]);
1005                 if (gdbackups < 0) {
1006                         brelse(primary[res]);
1007                         err = gdbackups;
1008                         goto exit_bh;
1009                 }
1010                 if (++data >= end)
1011                         data = (__le32 *)dind->b_data;
1012         }
1013
1014         for (i = 0; i < reserved_gdb; i++) {
1015                 BUFFER_TRACE(primary[i], "get_write_access");
1016                 if ((err = ext4_journal_get_write_access(handle, primary[i])))
1017                         goto exit_bh;
1018         }
1019
1020         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
1021                 goto exit_bh;
1022
1023         /*
1024          * Finally we can add each of the reserved backup GDT blocks from
1025          * the new group to its reserved primary GDT block.
1026          */
1027         blk = group * EXT4_BLOCKS_PER_GROUP(sb);
1028         for (i = 0; i < reserved_gdb; i++) {
1029                 int err2;
1030                 data = (__le32 *)primary[i]->b_data;
1031                 /* printk("reserving backup %lu[%u] = %lu\n",
1032                        primary[i]->b_blocknr, gdbackups,
1033                        blk + primary[i]->b_blocknr); */
1034                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
1035                 err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
1036                 if (!err)
1037                         err = err2;
1038         }
1039
1040         inode->i_blocks += reserved_gdb * sb->s_blocksize >> (9 - cluster_bits);
1041         ext4_mark_iloc_dirty(handle, inode, &iloc);
1042
1043 exit_bh:
1044         while (--res >= 0)
1045                 brelse(primary[res]);
1046         brelse(dind);
1047
1048 exit_free:
1049         kfree(primary);
1050
1051         return err;
1052 }
1053
1054 /*
1055  * Update the backup copies of the ext4 metadata.  These don't need to be part
1056  * of the main resize transaction, because e2fsck will re-write them if there
1057  * is a problem (basically only OOM will cause a problem).  However, we
1058  * _should_ update the backups if possible, in case the primary gets trashed
1059  * for some reason and we need to run e2fsck from a backup superblock.  The
1060  * important part is that the new block and inode counts are in the backup
1061  * superblocks, and the location of the new group metadata in the GDT backups.
1062  *
1063  * We do not need take the s_resize_lock for this, because these
1064  * blocks are not otherwise touched by the filesystem code when it is
1065  * mounted.  We don't need to worry about last changing from
1066  * sbi->s_groups_count, because the worst that can happen is that we
1067  * do not copy the full number of backups at this time.  The resize
1068  * which changed s_groups_count will backup again.
1069  */
1070 static void update_backups(struct super_block *sb, sector_t blk_off, char *data,
1071                            int size, int meta_bg)
1072 {
1073         struct ext4_sb_info *sbi = EXT4_SB(sb);
1074         ext4_group_t last;
1075         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
1076         unsigned three = 1;
1077         unsigned five = 5;
1078         unsigned seven = 7;
1079         ext4_group_t group = 0;
1080         int rest = sb->s_blocksize - size;
1081         handle_t *handle;
1082         int err = 0, err2;
1083
1084         handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, EXT4_MAX_TRANS_DATA);
1085         if (IS_ERR(handle)) {
1086                 group = 1;
1087                 err = PTR_ERR(handle);
1088                 goto exit_err;
1089         }
1090
1091         if (meta_bg == 0) {
1092                 group = ext4_list_backups(sb, &three, &five, &seven);
1093                 last = sbi->s_groups_count;
1094         } else {
1095                 group = ext4_get_group_number(sb, blk_off) + 1;
1096                 last = (ext4_group_t)(group + EXT4_DESC_PER_BLOCK(sb) - 2);
1097         }
1098
1099         while (group < sbi->s_groups_count) {
1100                 struct buffer_head *bh;
1101                 ext4_fsblk_t backup_block;
1102
1103                 /* Out of journal space, and can't get more - abort - so sad */
1104                 if (ext4_handle_valid(handle) &&
1105                     handle->h_buffer_credits == 0 &&
1106                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
1107                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
1108                         break;
1109
1110                 if (meta_bg == 0)
1111                         backup_block = ((ext4_fsblk_t)group) * bpg + blk_off;
1112                 else
1113                         backup_block = (ext4_group_first_block_no(sb, group) +
1114                                         ext4_bg_has_super(sb, group));
1115
1116                 bh = sb_getblk(sb, backup_block);
1117                 if (unlikely(!bh)) {
1118                         err = -ENOMEM;
1119                         break;
1120                 }
1121                 ext4_debug("update metadata backup %llu(+%llu)\n",
1122                            backup_block, backup_block -
1123                            ext4_group_first_block_no(sb, group));
1124                 BUFFER_TRACE(bh, "get_write_access");
1125                 if ((err = ext4_journal_get_write_access(handle, bh))) {
1126                         brelse(bh);
1127                         break;
1128                 }
1129                 lock_buffer(bh);
1130                 memcpy(bh->b_data, data, size);
1131                 if (rest)
1132                         memset(bh->b_data + size, 0, rest);
1133                 set_buffer_uptodate(bh);
1134                 unlock_buffer(bh);
1135                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
1136                 if (unlikely(err))
1137                         ext4_std_error(sb, err);
1138                 brelse(bh);
1139
1140                 if (meta_bg == 0)
1141                         group = ext4_list_backups(sb, &three, &five, &seven);
1142                 else if (group == last)
1143                         break;
1144                 else
1145                         group = last;
1146         }
1147         if ((err2 = ext4_journal_stop(handle)) && !err)
1148                 err = err2;
1149
1150         /*
1151          * Ugh! Need to have e2fsck write the backup copies.  It is too
1152          * late to revert the resize, we shouldn't fail just because of
1153          * the backup copies (they are only needed in case of corruption).
1154          *
1155          * However, if we got here we have a journal problem too, so we
1156          * can't really start a transaction to mark the superblock.
1157          * Chicken out and just set the flag on the hope it will be written
1158          * to disk, and if not - we will simply wait until next fsck.
1159          */
1160 exit_err:
1161         if (err) {
1162                 ext4_warning(sb, "can't update backup for group %u (err %d), "
1163                              "forcing fsck on next reboot", group, err);
1164                 sbi->s_mount_state &= ~EXT4_VALID_FS;
1165                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
1166                 mark_buffer_dirty(sbi->s_sbh);
1167         }
1168 }
1169
1170 /*
1171  * ext4_add_new_descs() adds @count group descriptor of groups
1172  * starting at @group
1173  *
1174  * @handle: journal handle
1175  * @sb: super block
1176  * @group: the group no. of the first group desc to be added
1177  * @resize_inode: the resize inode
1178  * @count: number of group descriptors to be added
1179  */
1180 static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
1181                               ext4_group_t group, struct inode *resize_inode,
1182                               ext4_group_t count)
1183 {
1184         struct ext4_sb_info *sbi = EXT4_SB(sb);
1185         struct ext4_super_block *es = sbi->s_es;
1186         struct buffer_head *gdb_bh;
1187         int i, gdb_off, gdb_num, err = 0;
1188         int meta_bg;
1189
1190         meta_bg = ext4_has_feature_meta_bg(sb);
1191         for (i = 0; i < count; i++, group++) {
1192                 int reserved_gdb = ext4_bg_has_super(sb, group) ?
1193                         le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1194
1195                 gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1196                 gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1197
1198                 /*
1199                  * We will only either add reserved group blocks to a backup group
1200                  * or remove reserved blocks for the first group in a new group block.
1201                  * Doing both would be mean more complex code, and sane people don't
1202                  * use non-sparse filesystems anymore.  This is already checked above.
1203                  */
1204                 if (gdb_off) {
1205                         gdb_bh = sbi->s_group_desc[gdb_num];
1206                         BUFFER_TRACE(gdb_bh, "get_write_access");
1207                         err = ext4_journal_get_write_access(handle, gdb_bh);
1208
1209                         if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))
1210                                 err = reserve_backup_gdb(handle, resize_inode, group);
1211                 } else if (meta_bg != 0) {
1212                         err = add_new_gdb_meta_bg(sb, handle, group);
1213                 } else {
1214                         err = add_new_gdb(handle, resize_inode, group);
1215                 }
1216                 if (err)
1217                         break;
1218         }
1219         return err;
1220 }
1221
1222 static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
1223 {
1224         struct buffer_head *bh = sb_getblk(sb, block);
1225         if (unlikely(!bh))
1226                 return NULL;
1227         if (!bh_uptodate_or_lock(bh)) {
1228                 if (bh_submit_read(bh) < 0) {
1229                         brelse(bh);
1230                         return NULL;
1231                 }
1232         }
1233
1234         return bh;
1235 }
1236
1237 static int ext4_set_bitmap_checksums(struct super_block *sb,
1238                                      ext4_group_t group,
1239                                      struct ext4_group_desc *gdp,
1240                                      struct ext4_new_group_data *group_data)
1241 {
1242         struct buffer_head *bh;
1243
1244         if (!ext4_has_metadata_csum(sb))
1245                 return 0;
1246
1247         bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
1248         if (!bh)
1249                 return -EIO;
1250         ext4_inode_bitmap_csum_set(sb, group, gdp, bh,
1251                                    EXT4_INODES_PER_GROUP(sb) / 8);
1252         brelse(bh);
1253
1254         bh = ext4_get_bitmap(sb, group_data->block_bitmap);
1255         if (!bh)
1256                 return -EIO;
1257         ext4_block_bitmap_csum_set(sb, group, gdp, bh);
1258         brelse(bh);
1259
1260         return 0;
1261 }
1262
1263 /*
1264  * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
1265  */
1266 static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
1267                                 struct ext4_new_flex_group_data *flex_gd)
1268 {
1269         struct ext4_new_group_data      *group_data = flex_gd->groups;
1270         struct ext4_group_desc          *gdp;
1271         struct ext4_sb_info             *sbi = EXT4_SB(sb);
1272         struct buffer_head              *gdb_bh;
1273         ext4_group_t                    group;
1274         __u16                           *bg_flags = flex_gd->bg_flags;
1275         int                             i, gdb_off, gdb_num, err = 0;
1276
1277
1278         for (i = 0; i < flex_gd->count; i++, group_data++, bg_flags++) {
1279                 group = group_data->group;
1280
1281                 gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1282                 gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1283
1284                 /*
1285                  * get_write_access() has been called on gdb_bh by ext4_add_new_desc().
1286                  */
1287                 gdb_bh = sbi->s_group_desc[gdb_num];
1288                 /* Update group descriptor block for new group */
1289                 gdp = (struct ext4_group_desc *)(gdb_bh->b_data +
1290                                                  gdb_off * EXT4_DESC_SIZE(sb));
1291
1292                 memset(gdp, 0, EXT4_DESC_SIZE(sb));
1293                 ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
1294                 ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
1295                 err = ext4_set_bitmap_checksums(sb, group, gdp, group_data);
1296                 if (err) {
1297                         ext4_std_error(sb, err);
1298                         break;
1299                 }
1300
1301                 ext4_inode_table_set(sb, gdp, group_data->inode_table);
1302                 ext4_free_group_clusters_set(sb, gdp,
1303                                              group_data->free_clusters_count);
1304                 ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
1305                 if (ext4_has_group_desc_csum(sb))
1306                         ext4_itable_unused_set(sb, gdp,
1307                                                EXT4_INODES_PER_GROUP(sb));
1308                 gdp->bg_flags = cpu_to_le16(*bg_flags);
1309                 ext4_group_desc_csum_set(sb, group, gdp);
1310
1311                 err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
1312                 if (unlikely(err)) {
1313                         ext4_std_error(sb, err);
1314                         break;
1315                 }
1316
1317                 /*
1318                  * We can allocate memory for mb_alloc based on the new group
1319                  * descriptor
1320                  */
1321                 err = ext4_mb_add_groupinfo(sb, group, gdp);
1322                 if (err)
1323                         break;
1324         }
1325         return err;
1326 }
1327
1328 /*
1329  * ext4_update_super() updates the super block so that the newly added
1330  * groups can be seen by the filesystem.
1331  *
1332  * @sb: super block
1333  * @flex_gd: new added groups
1334  */
1335 static void ext4_update_super(struct super_block *sb,
1336                              struct ext4_new_flex_group_data *flex_gd)
1337 {
1338         ext4_fsblk_t blocks_count = 0;
1339         ext4_fsblk_t free_blocks = 0;
1340         ext4_fsblk_t reserved_blocks = 0;
1341         struct ext4_new_group_data *group_data = flex_gd->groups;
1342         struct ext4_sb_info *sbi = EXT4_SB(sb);
1343         struct ext4_super_block *es = sbi->s_es;
1344         int i;
1345
1346         BUG_ON(flex_gd->count == 0 || group_data == NULL);
1347         /*
1348          * Make the new blocks and inodes valid next.  We do this before
1349          * increasing the group count so that once the group is enabled,
1350          * all of its blocks and inodes are already valid.
1351          *
1352          * We always allocate group-by-group, then block-by-block or
1353          * inode-by-inode within a group, so enabling these
1354          * blocks/inodes before the group is live won't actually let us
1355          * allocate the new space yet.
1356          */
1357         for (i = 0; i < flex_gd->count; i++) {
1358                 blocks_count += group_data[i].blocks_count;
1359                 free_blocks += EXT4_C2B(sbi, group_data[i].free_clusters_count);
1360         }
1361
1362         reserved_blocks = ext4_r_blocks_count(es) * 100;
1363         reserved_blocks = div64_u64(reserved_blocks, ext4_blocks_count(es));
1364         reserved_blocks *= blocks_count;
1365         do_div(reserved_blocks, 100);
1366
1367         ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
1368         ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + free_blocks);
1369         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1370                      flex_gd->count);
1371         le32_add_cpu(&es->s_free_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1372                      flex_gd->count);
1373
1374         ext4_debug("free blocks count %llu", ext4_free_blocks_count(es));
1375         /*
1376          * We need to protect s_groups_count against other CPUs seeing
1377          * inconsistent state in the superblock.
1378          *
1379          * The precise rules we use are:
1380          *
1381          * * Writers must perform a smp_wmb() after updating all
1382          *   dependent data and before modifying the groups count
1383          *
1384          * * Readers must perform an smp_rmb() after reading the groups
1385          *   count and before reading any dependent data.
1386          *
1387          * NB. These rules can be relaxed when checking the group count
1388          * while freeing data, as we can only allocate from a block
1389          * group after serialising against the group count, and we can
1390          * only then free after serialising in turn against that
1391          * allocation.
1392          */
1393         smp_wmb();
1394
1395         /* Update the global fs size fields */
1396         sbi->s_groups_count += flex_gd->count;
1397         sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
1398                         (EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
1399
1400         /* Update the reserved block counts only once the new group is
1401          * active. */
1402         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
1403                                 reserved_blocks);
1404
1405         /* Update the free space counts */
1406         percpu_counter_add(&sbi->s_freeclusters_counter,
1407                            EXT4_NUM_B2C(sbi, free_blocks));
1408         percpu_counter_add(&sbi->s_freeinodes_counter,
1409                            EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
1410
1411         ext4_debug("free blocks count %llu",
1412                    percpu_counter_read(&sbi->s_freeclusters_counter));
1413         if (ext4_has_feature_flex_bg(sb) && sbi->s_log_groups_per_flex) {
1414                 ext4_group_t flex_group;
1415                 flex_group = ext4_flex_group(sbi, group_data[0].group);
1416                 atomic64_add(EXT4_NUM_B2C(sbi, free_blocks),
1417                              &sbi->s_flex_groups[flex_group].free_clusters);
1418                 atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
1419                            &sbi->s_flex_groups[flex_group].free_inodes);
1420         }
1421
1422         /*
1423          * Update the fs overhead information
1424          */
1425         ext4_calculate_overhead(sb);
1426
1427         if (test_opt(sb, DEBUG))
1428                 printk(KERN_DEBUG "EXT4-fs: added group %u:"
1429                        "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
1430                        blocks_count, free_blocks, reserved_blocks);
1431 }
1432
1433 /* Add a flex group to an fs. Ensure we handle all possible error conditions
1434  * _before_ we start modifying the filesystem, because we cannot abort the
1435  * transaction and not have it write the data to disk.
1436  */
1437 static int ext4_flex_group_add(struct super_block *sb,
1438                                struct inode *resize_inode,
1439                                struct ext4_new_flex_group_data *flex_gd)
1440 {
1441         struct ext4_sb_info *sbi = EXT4_SB(sb);
1442         struct ext4_super_block *es = sbi->s_es;
1443         ext4_fsblk_t o_blocks_count;
1444         ext4_grpblk_t last;
1445         ext4_group_t group;
1446         handle_t *handle;
1447         unsigned reserved_gdb;
1448         int err = 0, err2 = 0, credit;
1449
1450         BUG_ON(!flex_gd->count || !flex_gd->groups || !flex_gd->bg_flags);
1451
1452         reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
1453         o_blocks_count = ext4_blocks_count(es);
1454         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1455         BUG_ON(last);
1456
1457         err = setup_new_flex_group_blocks(sb, flex_gd);
1458         if (err)
1459                 goto exit;
1460         /*
1461          * We will always be modifying at least the superblock and  GDT
1462          * blocks.  If we are adding a group past the last current GDT block,
1463          * we will also modify the inode and the dindirect block.  If we
1464          * are adding a group with superblock/GDT backups  we will also
1465          * modify each of the reserved GDT dindirect blocks.
1466          */
1467         credit = 3;     /* sb, resize inode, resize inode dindirect */
1468         /* GDT blocks */
1469         credit += 1 + DIV_ROUND_UP(flex_gd->count, EXT4_DESC_PER_BLOCK(sb));
1470         credit += reserved_gdb; /* Reserved GDT dindirect blocks */
1471         handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credit);
1472         if (IS_ERR(handle)) {
1473                 err = PTR_ERR(handle);
1474                 goto exit;
1475         }
1476
1477         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1478         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1479         if (err)
1480                 goto exit_journal;
1481
1482         group = flex_gd->groups[0].group;
1483         BUG_ON(group != sbi->s_groups_count);
1484         err = ext4_add_new_descs(handle, sb, group,
1485                                 resize_inode, flex_gd->count);
1486         if (err)
1487                 goto exit_journal;
1488
1489         err = ext4_setup_new_descs(handle, sb, flex_gd);
1490         if (err)
1491                 goto exit_journal;
1492
1493         ext4_update_super(sb, flex_gd);
1494
1495         err = ext4_handle_dirty_super(handle, sb);
1496
1497 exit_journal:
1498         err2 = ext4_journal_stop(handle);
1499         if (!err)
1500                 err = err2;
1501
1502         if (!err) {
1503                 int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1504                 int gdb_num_end = ((group + flex_gd->count - 1) /
1505                                    EXT4_DESC_PER_BLOCK(sb));
1506                 int meta_bg = ext4_has_feature_meta_bg(sb);
1507                 sector_t old_gdb = 0;
1508
1509                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
1510                                sizeof(struct ext4_super_block), 0);
1511                 for (; gdb_num <= gdb_num_end; gdb_num++) {
1512                         struct buffer_head *gdb_bh;
1513
1514                         gdb_bh = sbi->s_group_desc[gdb_num];
1515                         if (old_gdb == gdb_bh->b_blocknr)
1516                                 continue;
1517                         update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
1518                                        gdb_bh->b_size, meta_bg);
1519                         old_gdb = gdb_bh->b_blocknr;
1520                 }
1521         }
1522 exit:
1523         return err;
1524 }
1525
1526 static int ext4_setup_next_flex_gd(struct super_block *sb,
1527                                     struct ext4_new_flex_group_data *flex_gd,
1528                                     ext4_fsblk_t n_blocks_count,
1529                                     unsigned long flexbg_size)
1530 {
1531         struct ext4_sb_info *sbi = EXT4_SB(sb);
1532         struct ext4_super_block *es = sbi->s_es;
1533         struct ext4_new_group_data *group_data = flex_gd->groups;
1534         ext4_fsblk_t o_blocks_count;
1535         ext4_group_t n_group;
1536         ext4_group_t group;
1537         ext4_group_t last_group;
1538         ext4_grpblk_t last;
1539         ext4_grpblk_t clusters_per_group;
1540         unsigned long i;
1541
1542         clusters_per_group = EXT4_CLUSTERS_PER_GROUP(sb);
1543
1544         o_blocks_count = ext4_blocks_count(es);
1545
1546         if (o_blocks_count == n_blocks_count)
1547                 return 0;
1548
1549         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1550         BUG_ON(last);
1551         ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
1552
1553         last_group = group | (flexbg_size - 1);
1554         if (last_group > n_group)
1555                 last_group = n_group;
1556
1557         flex_gd->count = last_group - group + 1;
1558
1559         for (i = 0; i < flex_gd->count; i++) {
1560                 int overhead;
1561
1562                 group_data[i].group = group + i;
1563                 group_data[i].blocks_count = EXT4_BLOCKS_PER_GROUP(sb);
1564                 overhead = ext4_group_overhead_blocks(sb, group + i);
1565                 group_data[i].mdata_blocks = overhead;
1566                 group_data[i].free_clusters_count = EXT4_CLUSTERS_PER_GROUP(sb);
1567                 if (ext4_has_group_desc_csum(sb)) {
1568                         flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
1569                                                EXT4_BG_INODE_UNINIT;
1570                         if (!test_opt(sb, INIT_INODE_TABLE))
1571                                 flex_gd->bg_flags[i] |= EXT4_BG_INODE_ZEROED;
1572                 } else
1573                         flex_gd->bg_flags[i] = EXT4_BG_INODE_ZEROED;
1574         }
1575
1576         if (last_group == n_group && ext4_has_group_desc_csum(sb))
1577                 /* We need to initialize block bitmap of last group. */
1578                 flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
1579
1580         if ((last_group == n_group) && (last != clusters_per_group - 1)) {
1581                 group_data[i - 1].blocks_count = EXT4_C2B(sbi, last + 1);
1582                 group_data[i - 1].free_clusters_count -= clusters_per_group -
1583                                                        last - 1;
1584         }
1585
1586         return 1;
1587 }
1588
1589 /* Add group descriptor data to an existing or new group descriptor block.
1590  * Ensure we handle all possible error conditions _before_ we start modifying
1591  * the filesystem, because we cannot abort the transaction and not have it
1592  * write the data to disk.
1593  *
1594  * If we are on a GDT block boundary, we need to get the reserved GDT block.
1595  * Otherwise, we may need to add backup GDT blocks for a sparse group.
1596  *
1597  * We only need to hold the superblock lock while we are actually adding
1598  * in the new group's counts to the superblock.  Prior to that we have
1599  * not really "added" the group at all.  We re-check that we are still
1600  * adding in the last group in case things have changed since verifying.
1601  */
1602 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
1603 {
1604         struct ext4_new_flex_group_data flex_gd;
1605         struct ext4_sb_info *sbi = EXT4_SB(sb);
1606         struct ext4_super_block *es = sbi->s_es;
1607         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
1608                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1609         struct inode *inode = NULL;
1610         int gdb_off;
1611         int err;
1612         __u16 bg_flags = 0;
1613
1614         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
1615
1616         if (gdb_off == 0 && !ext4_has_feature_sparse_super(sb)) {
1617                 ext4_warning(sb, "Can't resize non-sparse filesystem further");
1618                 return -EPERM;
1619         }
1620
1621         if (ext4_blocks_count(es) + input->blocks_count <
1622             ext4_blocks_count(es)) {
1623                 ext4_warning(sb, "blocks_count overflow");
1624                 return -EINVAL;
1625         }
1626
1627         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
1628             le32_to_cpu(es->s_inodes_count)) {
1629                 ext4_warning(sb, "inodes_count overflow");
1630                 return -EINVAL;
1631         }
1632
1633         if (reserved_gdb || gdb_off == 0) {
1634                 if (!ext4_has_feature_resize_inode(sb) ||
1635                     !le16_to_cpu(es->s_reserved_gdt_blocks)) {
1636                         ext4_warning(sb,
1637                                      "No reserved GDT blocks, can't resize");
1638                         return -EPERM;
1639                 }
1640                 inode = ext4_iget(sb, EXT4_RESIZE_INO, EXT4_IGET_SPECIAL);
1641                 if (IS_ERR(inode)) {
1642                         ext4_warning(sb, "Error opening resize inode");
1643                         return PTR_ERR(inode);
1644                 }
1645         }
1646
1647
1648         err = verify_group_input(sb, input);
1649         if (err)
1650                 goto out;
1651
1652         err = ext4_alloc_flex_bg_array(sb, input->group + 1);
1653         if (err)
1654                 goto out;
1655
1656         err = ext4_mb_alloc_groupinfo(sb, input->group + 1);
1657         if (err)
1658                 goto out;
1659
1660         flex_gd.count = 1;
1661         flex_gd.groups = input;
1662         flex_gd.bg_flags = &bg_flags;
1663         err = ext4_flex_group_add(sb, inode, &flex_gd);
1664 out:
1665         iput(inode);
1666         return err;
1667 } /* ext4_group_add */
1668
1669 /*
1670  * extend a group without checking assuming that checking has been done.
1671  */
1672 static int ext4_group_extend_no_check(struct super_block *sb,
1673                                       ext4_fsblk_t o_blocks_count, ext4_grpblk_t add)
1674 {
1675         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1676         handle_t *handle;
1677         int err = 0, err2;
1678
1679         /* We will update the superblock, one block bitmap, and
1680          * one group descriptor via ext4_group_add_blocks().
1681          */
1682         handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, 3);
1683         if (IS_ERR(handle)) {
1684                 err = PTR_ERR(handle);
1685                 ext4_warning(sb, "error %d on journal start", err);
1686                 return err;
1687         }
1688
1689         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
1690         err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
1691         if (err) {
1692                 ext4_warning(sb, "error %d on journal write access", err);
1693                 goto errout;
1694         }
1695
1696         ext4_blocks_count_set(es, o_blocks_count + add);
1697         ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + add);
1698         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1699                    o_blocks_count + add);
1700         /* We add the blocks to the bitmap and set the group need init bit */
1701         err = ext4_group_add_blocks(handle, sb, o_blocks_count, add);
1702         if (err)
1703                 goto errout;
1704         ext4_handle_dirty_super(handle, sb);
1705         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1706                    o_blocks_count + add);
1707 errout:
1708         err2 = ext4_journal_stop(handle);
1709         if (err2 && !err)
1710                 err = err2;
1711
1712         if (!err) {
1713                 if (test_opt(sb, DEBUG))
1714                         printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
1715                                "blocks\n", ext4_blocks_count(es));
1716                 update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
1717                                (char *)es, sizeof(struct ext4_super_block), 0);
1718         }
1719         return err;
1720 }
1721
1722 /*
1723  * Extend the filesystem to the new number of blocks specified.  This entry
1724  * point is only used to extend the current filesystem to the end of the last
1725  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
1726  * for emergencies (because it has no dependencies on reserved blocks).
1727  *
1728  * If we _really_ wanted, we could use default values to call ext4_group_add()
1729  * allow the "remount" trick to work for arbitrary resizing, assuming enough
1730  * GDT blocks are reserved to grow to the desired size.
1731  */
1732 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1733                       ext4_fsblk_t n_blocks_count)
1734 {
1735         ext4_fsblk_t o_blocks_count;
1736         ext4_grpblk_t last;
1737         ext4_grpblk_t add;
1738         struct buffer_head *bh;
1739         int err;
1740         ext4_group_t group;
1741
1742         o_blocks_count = ext4_blocks_count(es);
1743
1744         if (test_opt(sb, DEBUG))
1745                 ext4_msg(sb, KERN_DEBUG,
1746                          "extending last group from %llu to %llu blocks",
1747                          o_blocks_count, n_blocks_count);
1748
1749         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1750                 return 0;
1751
1752         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1753                 ext4_msg(sb, KERN_ERR,
1754                          "filesystem too large to resize to %llu blocks safely",
1755                          n_blocks_count);
1756                 if (sizeof(sector_t) < 8)
1757                         ext4_warning(sb, "CONFIG_LBDAF not enabled");
1758                 return -EINVAL;
1759         }
1760
1761         if (n_blocks_count < o_blocks_count) {
1762                 ext4_warning(sb, "can't shrink FS - resize aborted");
1763                 return -EINVAL;
1764         }
1765
1766         /* Handle the remaining blocks in the last group only. */
1767         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1768
1769         if (last == 0) {
1770                 ext4_warning(sb, "need to use ext2online to resize further");
1771                 return -EPERM;
1772         }
1773
1774         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1775
1776         if (o_blocks_count + add < o_blocks_count) {
1777                 ext4_warning(sb, "blocks_count overflow");
1778                 return -EINVAL;
1779         }
1780
1781         if (o_blocks_count + add > n_blocks_count)
1782                 add = n_blocks_count - o_blocks_count;
1783
1784         if (o_blocks_count + add < n_blocks_count)
1785                 ext4_warning(sb, "will only finish group (%llu blocks, %u new)",
1786                              o_blocks_count + add, add);
1787
1788         /* See if the device is actually as big as what was requested */
1789         bh = sb_bread(sb, o_blocks_count + add - 1);
1790         if (!bh) {
1791                 ext4_warning(sb, "can't read last block, resize aborted");
1792                 return -ENOSPC;
1793         }
1794         brelse(bh);
1795
1796         err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1797         return err;
1798 } /* ext4_group_extend */
1799
1800
1801 static int num_desc_blocks(struct super_block *sb, ext4_group_t groups)
1802 {
1803         return (groups + EXT4_DESC_PER_BLOCK(sb) - 1) / EXT4_DESC_PER_BLOCK(sb);
1804 }
1805
1806 /*
1807  * Release the resize inode and drop the resize_inode feature if there
1808  * are no more reserved gdt blocks, and then convert the file system
1809  * to enable meta_bg
1810  */
1811 static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
1812 {
1813         handle_t *handle;
1814         struct ext4_sb_info *sbi = EXT4_SB(sb);
1815         struct ext4_super_block *es = sbi->s_es;
1816         struct ext4_inode_info *ei = EXT4_I(inode);
1817         ext4_fsblk_t nr;
1818         int i, ret, err = 0;
1819         int credits = 1;
1820
1821         ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
1822         if (inode) {
1823                 if (es->s_reserved_gdt_blocks) {
1824                         ext4_error(sb, "Unexpected non-zero "
1825                                    "s_reserved_gdt_blocks");
1826                         return -EPERM;
1827                 }
1828
1829                 /* Do a quick sanity check of the resize inode */
1830                 if (inode->i_blocks != 1 << (inode->i_blkbits -
1831                                              (9 - sbi->s_cluster_bits)))
1832                         goto invalid_resize_inode;
1833                 for (i = 0; i < EXT4_N_BLOCKS; i++) {
1834                         if (i == EXT4_DIND_BLOCK) {
1835                                 if (ei->i_data[i])
1836                                         continue;
1837                                 else
1838                                         goto invalid_resize_inode;
1839                         }
1840                         if (ei->i_data[i])
1841                                 goto invalid_resize_inode;
1842                 }
1843                 credits += 3;   /* block bitmap, bg descriptor, resize inode */
1844         }
1845
1846         handle = ext4_journal_start_sb(sb, EXT4_HT_RESIZE, credits);
1847         if (IS_ERR(handle))
1848                 return PTR_ERR(handle);
1849
1850         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
1851         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1852         if (err)
1853                 goto errout;
1854
1855         ext4_clear_feature_resize_inode(sb);
1856         ext4_set_feature_meta_bg(sb);
1857         sbi->s_es->s_first_meta_bg =
1858                 cpu_to_le32(num_desc_blocks(sb, sbi->s_groups_count));
1859
1860         err = ext4_handle_dirty_super(handle, sb);
1861         if (err) {
1862                 ext4_std_error(sb, err);
1863                 goto errout;
1864         }
1865
1866         if (inode) {
1867                 nr = le32_to_cpu(ei->i_data[EXT4_DIND_BLOCK]);
1868                 ext4_free_blocks(handle, inode, NULL, nr, 1,
1869                                  EXT4_FREE_BLOCKS_METADATA |
1870                                  EXT4_FREE_BLOCKS_FORGET);
1871                 ei->i_data[EXT4_DIND_BLOCK] = 0;
1872                 inode->i_blocks = 0;
1873
1874                 err = ext4_mark_inode_dirty(handle, inode);
1875                 if (err)
1876                         ext4_std_error(sb, err);
1877         }
1878
1879 errout:
1880         ret = ext4_journal_stop(handle);
1881         if (!err)
1882                 err = ret;
1883         return ret;
1884
1885 invalid_resize_inode:
1886         ext4_error(sb, "corrupted/inconsistent resize inode");
1887         return -EINVAL;
1888 }
1889
1890 /*
1891  * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
1892  *
1893  * @sb: super block of the fs to be resized
1894  * @n_blocks_count: the number of blocks resides in the resized fs
1895  */
1896 int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
1897 {
1898         struct ext4_new_flex_group_data *flex_gd = NULL;
1899         struct ext4_sb_info *sbi = EXT4_SB(sb);
1900         struct ext4_super_block *es = sbi->s_es;
1901         struct buffer_head *bh;
1902         struct inode *resize_inode = NULL;
1903         ext4_grpblk_t add, offset;
1904         unsigned long n_desc_blocks;
1905         unsigned long o_desc_blocks;
1906         ext4_group_t o_group;
1907         ext4_group_t n_group;
1908         ext4_fsblk_t o_blocks_count;
1909         ext4_fsblk_t n_blocks_count_retry = 0;
1910         unsigned long last_update_time = 0;
1911         int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
1912         int meta_bg;
1913
1914         /* See if the device is actually as big as what was requested */
1915         bh = sb_bread(sb, n_blocks_count - 1);
1916         if (!bh) {
1917                 ext4_warning(sb, "can't read last block, resize aborted");
1918                 return -ENOSPC;
1919         }
1920         brelse(bh);
1921
1922 retry:
1923         o_blocks_count = ext4_blocks_count(es);
1924
1925         ext4_msg(sb, KERN_INFO, "resizing filesystem from %llu "
1926                  "to %llu blocks", o_blocks_count, n_blocks_count);
1927
1928         if (n_blocks_count < o_blocks_count) {
1929                 /* On-line shrinking not supported */
1930                 ext4_warning(sb, "can't shrink FS - resize aborted");
1931                 return -EINVAL;
1932         }
1933
1934         if (n_blocks_count == o_blocks_count)
1935                 /* Nothing need to do */
1936                 return 0;
1937
1938         n_group = ext4_get_group_number(sb, n_blocks_count - 1);
1939         if (n_group >= (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) {
1940                 ext4_warning(sb, "resize would cause inodes_count overflow");
1941                 return -EINVAL;
1942         }
1943         ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);
1944
1945         n_desc_blocks = num_desc_blocks(sb, n_group + 1);
1946         o_desc_blocks = num_desc_blocks(sb, sbi->s_groups_count);
1947
1948         meta_bg = ext4_has_feature_meta_bg(sb);
1949
1950         if (ext4_has_feature_resize_inode(sb)) {
1951                 if (meta_bg) {
1952                         ext4_error(sb, "resize_inode and meta_bg enabled "
1953                                    "simultaneously");
1954                         return -EINVAL;
1955                 }
1956                 if (n_desc_blocks > o_desc_blocks +
1957                     le16_to_cpu(es->s_reserved_gdt_blocks)) {
1958                         n_blocks_count_retry = n_blocks_count;
1959                         n_desc_blocks = o_desc_blocks +
1960                                 le16_to_cpu(es->s_reserved_gdt_blocks);
1961                         n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb);
1962                         n_blocks_count = (ext4_fsblk_t)n_group *
1963                                 EXT4_BLOCKS_PER_GROUP(sb);
1964                         n_group--; /* set to last group number */
1965                 }
1966
1967                 if (!resize_inode)
1968                         resize_inode = ext4_iget(sb, EXT4_RESIZE_INO,
1969                                                  EXT4_IGET_SPECIAL);
1970                 if (IS_ERR(resize_inode)) {
1971                         ext4_warning(sb, "Error opening resize inode");
1972                         return PTR_ERR(resize_inode);
1973                 }
1974         }
1975
1976         if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
1977                 err = ext4_convert_meta_bg(sb, resize_inode);
1978                 if (err)
1979                         goto out;
1980                 if (resize_inode) {
1981                         iput(resize_inode);
1982                         resize_inode = NULL;
1983                 }
1984                 if (n_blocks_count_retry) {
1985                         n_blocks_count = n_blocks_count_retry;
1986                         n_blocks_count_retry = 0;
1987                         goto retry;
1988                 }
1989         }
1990
1991         /*
1992          * Make sure the last group has enough space so that it's
1993          * guaranteed to have enough space for all metadata blocks
1994          * that it might need to hold.  (We might not need to store
1995          * the inode table blocks in the last block group, but there
1996          * will be cases where this might be needed.)
1997          */
1998         if ((ext4_group_first_block_no(sb, n_group) +
1999              ext4_group_overhead_blocks(sb, n_group) + 2 +
2000              sbi->s_itb_per_group + sbi->s_cluster_ratio) >= n_blocks_count) {
2001                 n_blocks_count = ext4_group_first_block_no(sb, n_group);
2002                 n_group--;
2003                 n_blocks_count_retry = 0;
2004                 if (resize_inode) {
2005                         iput(resize_inode);
2006                         resize_inode = NULL;
2007                 }
2008                 goto retry;
2009         }
2010
2011         /* extend the last group */
2012         if (n_group == o_group)
2013                 add = n_blocks_count - o_blocks_count;
2014         else
2015                 add = EXT4_C2B(sbi, EXT4_CLUSTERS_PER_GROUP(sb) - (offset + 1));
2016         if (add > 0) {
2017                 err = ext4_group_extend_no_check(sb, o_blocks_count, add);
2018                 if (err)
2019                         goto out;
2020         }
2021
2022         if (ext4_blocks_count(es) == n_blocks_count)
2023                 goto out;
2024
2025         err = ext4_alloc_flex_bg_array(sb, n_group + 1);
2026         if (err)
2027                 goto out;
2028
2029         err = ext4_mb_alloc_groupinfo(sb, n_group + 1);
2030         if (err)
2031                 goto out;
2032
2033         flex_gd = alloc_flex_gd(flexbg_size);
2034         if (flex_gd == NULL) {
2035                 err = -ENOMEM;
2036                 goto out;
2037         }
2038
2039         /* Add flex groups. Note that a regular group is a
2040          * flex group with 1 group.
2041          */
2042         while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
2043                                               flexbg_size)) {
2044                 if (jiffies - last_update_time > HZ * 10) {
2045                         if (last_update_time)
2046                                 ext4_msg(sb, KERN_INFO,
2047                                          "resized to %llu blocks",
2048                                          ext4_blocks_count(es));
2049                         last_update_time = jiffies;
2050                 }
2051                 if (ext4_alloc_group_tables(sb, flex_gd, flexbg_size) != 0)
2052                         break;
2053                 err = ext4_flex_group_add(sb, resize_inode, flex_gd);
2054                 if (unlikely(err))
2055                         break;
2056         }
2057
2058         if (!err && n_blocks_count_retry) {
2059                 n_blocks_count = n_blocks_count_retry;
2060                 n_blocks_count_retry = 0;
2061                 free_flex_gd(flex_gd);
2062                 flex_gd = NULL;
2063                 if (resize_inode) {
2064                         iput(resize_inode);
2065                         resize_inode = NULL;
2066                 }
2067                 goto retry;
2068         }
2069
2070 out:
2071         if (flex_gd)
2072                 free_flex_gd(flex_gd);
2073         if (resize_inode != NULL)
2074                 iput(resize_inode);
2075         ext4_msg(sb, KERN_INFO, "resized filesystem to %llu", n_blocks_count);
2076         return err;
2077 }