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 int ext4_resize_begin(struct super_block *sb)
  20 {
  21         int ret = 0;
  22
  23         if (!capable(CAP_SYS_RESOURCE))
  24                 return -EPERM;
  25
  26         /*
  27          * We are not allowed to do online-resizing on a filesystem mounted
  28          * with error, because it can destroy the filesystem easily.
  29          */
  30         if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
  31                 ext4_warning(sb, "There are errors in the filesystem, "
  32                              "so online resizing is not allowed\n");
  33                 return -EPERM;
  34         }
  35
  36         if (test_and_set_bit_lock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags))
  37                 ret = -EBUSY;
  38
  39         return ret;
  40 }
  41
  42 void ext4_resize_end(struct super_block *sb)
  43 {
  44         clear_bit_unlock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags);
  45         smp_mb__after_clear_bit();
  46 }
  47
  48 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
  49 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
  50
  51 static int verify_group_input(struct super_block *sb,
  52                               struct ext4_new_group_data *input)
  53 {
  54         struct ext4_sb_info *sbi = EXT4_SB(sb);
  55         struct ext4_super_block *es = sbi->s_es;
  56         ext4_fsblk_t start = ext4_blocks_count(es);
  57         ext4_fsblk_t end = start + input->blocks_count;
  58         ext4_group_t group = input->group;
  59         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
  60         unsigned overhead = ext4_bg_has_super(sb, group) ?
  61                 (1 + ext4_bg_num_gdb(sb, group) +
  62                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
  63         ext4_fsblk_t metaend = start + overhead;
  64         struct buffer_head *bh = NULL;
  65         ext4_grpblk_t free_blocks_count, offset;
  66         int err = -EINVAL;
  67
  68         input->free_blocks_count = free_blocks_count =
  69                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
  70
  71         if (test_opt(sb, DEBUG))
  72                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
  73                        "(%d free, %u reserved)\n",
  74                        ext4_bg_has_super(sb, input->group) ? "normal" :
  75                        "no-super", input->group, input->blocks_count,
  76                        free_blocks_count, input->reserved_blocks);
  77
  78         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
  79         if (group != sbi->s_groups_count)
  80                 ext4_warning(sb, "Cannot add at group %u (only %u groups)",
  81                              input->group, sbi->s_groups_count);
  82         else if (offset != 0)
  83                         ext4_warning(sb, "Last group not full");
  84         else if (input->reserved_blocks > input->blocks_count / 5)
  85                 ext4_warning(sb, "Reserved blocks too high (%u)",
  86                              input->reserved_blocks);
  87         else if (free_blocks_count < 0)
  88                 ext4_warning(sb, "Bad blocks count %u",
  89                              input->blocks_count);
  90         else if (!(bh = sb_bread(sb, end - 1)))
  91                 ext4_warning(sb, "Cannot read last block (%llu)",
  92                              end - 1);
  93         else if (outside(input->block_bitmap, start, end))
  94                 ext4_warning(sb, "Block bitmap not in group (block %llu)",
  95                              (unsigned long long)input->block_bitmap);
  96         else if (outside(input->inode_bitmap, start, end))
  97                 ext4_warning(sb, "Inode bitmap not in group (block %llu)",
  98                              (unsigned long long)input->inode_bitmap);
  99         else if (outside(input->inode_table, start, end) ||
 100                  outside(itend - 1, start, end))
 101                 ext4_warning(sb, "Inode table not in group (blocks %llu-%llu)",
 102                              (unsigned long long)input->inode_table, itend - 1);
 103         else if (input->inode_bitmap == input->block_bitmap)
 104                 ext4_warning(sb, "Block bitmap same as inode bitmap (%llu)",
 105                              (unsigned long long)input->block_bitmap);
 106         else if (inside(input->block_bitmap, input->inode_table, itend))
 107                 ext4_warning(sb, "Block bitmap (%llu) in inode table "
 108                              "(%llu-%llu)",
 109                              (unsigned long long)input->block_bitmap,
 110                              (unsigned long long)input->inode_table, itend - 1);
 111         else if (inside(input->inode_bitmap, input->inode_table, itend))
 112                 ext4_warning(sb, "Inode bitmap (%llu) in inode table "
 113                              "(%llu-%llu)",
 114                              (unsigned long long)input->inode_bitmap,
 115                              (unsigned long long)input->inode_table, itend - 1);
 116         else if (inside(input->block_bitmap, start, metaend))
 117                 ext4_warning(sb, "Block bitmap (%llu) in GDT table (%llu-%llu)",
 118                              (unsigned long long)input->block_bitmap,
 119                              start, metaend - 1);
 120         else if (inside(input->inode_bitmap, start, metaend))
 121                 ext4_warning(sb, "Inode bitmap (%llu) in GDT table (%llu-%llu)",
 122                              (unsigned long long)input->inode_bitmap,
 123                              start, metaend - 1);
 124         else if (inside(input->inode_table, start, metaend) ||
 125                  inside(itend - 1, start, metaend))
 126                 ext4_warning(sb, "Inode table (%llu-%llu) overlaps GDT table "
 127                              "(%llu-%llu)",
 128                              (unsigned long long)input->inode_table,
 129                              itend - 1, start, metaend - 1);
 130         else
 131                 err = 0;
 132         brelse(bh);
 133
 134         return err;
 135 }
 136
 137 /*
 138  * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
 139  * group each time.
 140  */
 141 struct ext4_new_flex_group_data {
 142         struct ext4_new_group_data *groups;     /* new_group_data for groups
 143                                                    in the flex group */
 144         __u16 *bg_flags;                        /* block group flags of groups
 145                                                    in @groups */
 146         ext4_group_t count;                     /* number of groups in @groups
 147                                                  */
 148 };
 149
 150 /*
 151  * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
 152  * @flexbg_size.
 153  *
 154  * Returns NULL on failure otherwise address of the allocated structure.
 155  */
 156 static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
 157 {
 158         struct ext4_new_flex_group_data *flex_gd;
 159
 160         flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
 161         if (flex_gd == NULL)
 162                 goto out3;
 163
 164         flex_gd->count = flexbg_size;
 165
 166         flex_gd->groups = kmalloc(sizeof(struct ext4_new_group_data) *
 167                                   flexbg_size, GFP_NOFS);
 168         if (flex_gd->groups == NULL)
 169                 goto out2;
 170
 171         flex_gd->bg_flags = kmalloc(flexbg_size * sizeof(__u16), GFP_NOFS);
 172         if (flex_gd->bg_flags == NULL)
 173                 goto out1;
 174
 175         return flex_gd;
 176
 177 out1:
 178         kfree(flex_gd->groups);
 179 out2:
 180         kfree(flex_gd);
 181 out3:
 182         return NULL;
 183 }
 184
 185 static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
 186 {
 187         kfree(flex_gd->bg_flags);
 188         kfree(flex_gd->groups);
 189         kfree(flex_gd);
 190 }
 191
 192 /*
 193  * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
 194  * and inode tables for a flex group.
 195  *
 196  * This function is used by 64bit-resize.  Note that this function allocates
 197  * group tables from the 1st group of groups contained by @flexgd, which may
 198  * be a partial of a flex group.
 199  *
 200  * @sb: super block of fs to which the groups belongs
 201  */
 202 static void ext4_alloc_group_tables(struct super_block *sb,
 203                                 struct ext4_new_flex_group_data *flex_gd,
 204                                 int flexbg_size)
 205 {
 206         struct ext4_new_group_data *group_data = flex_gd->groups;
 207         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 208         ext4_fsblk_t start_blk;
 209         ext4_fsblk_t last_blk;
 210         ext4_group_t src_group;
 211         ext4_group_t bb_index = 0;
 212         ext4_group_t ib_index = 0;
 213         ext4_group_t it_index = 0;
 214         ext4_group_t group;
 215         ext4_group_t last_group;
 216         unsigned overhead;
 217
 218         BUG_ON(flex_gd->count == 0 || group_data == NULL);
 219
 220         src_group = group_data[0].group;
 221         last_group  = src_group + flex_gd->count - 1;
 222
 223         BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
 224                (last_group & ~(flexbg_size - 1))));
 225 next_group:
 226         group = group_data[0].group;
 227         start_blk = ext4_group_first_block_no(sb, src_group);
 228         last_blk = start_blk + group_data[src_group - group].blocks_count;
 229
 230         overhead = ext4_bg_has_super(sb, src_group) ?
 231                    (1 + ext4_bg_num_gdb(sb, src_group) +
 232                     le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
 233
 234         start_blk += overhead;
 235
 236         BUG_ON(src_group >= group_data[0].group + flex_gd->count);
 237         /* We collect contiguous blocks as much as possible. */
 238         src_group++;
 239         for (; src_group <= last_group; src_group++)
 240                 if (!ext4_bg_has_super(sb, src_group))
 241                         last_blk += group_data[src_group - group].blocks_count;
 242                 else
 243                         break;
 244
 245         /* Allocate block bitmaps */
 246         for (; bb_index < flex_gd->count; bb_index++) {
 247                 if (start_blk >= last_blk)
 248                         goto next_group;
 249                 group_data[bb_index].block_bitmap = start_blk++;
 250                 ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
 251                 group -= group_data[0].group;
 252                 group_data[group].free_blocks_count--;
 253                 if (flexbg_size > 1)
 254                         flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
 255         }
 256
 257         /* Allocate inode bitmaps */
 258         for (; ib_index < flex_gd->count; ib_index++) {
 259                 if (start_blk >= last_blk)
 260                         goto next_group;
 261                 group_data[ib_index].inode_bitmap = start_blk++;
 262                 ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
 263                 group -= group_data[0].group;
 264                 group_data[group].free_blocks_count--;
 265                 if (flexbg_size > 1)
 266                         flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
 267         }
 268
 269         /* Allocate inode tables */
 270         for (; it_index < flex_gd->count; it_index++) {
 271                 if (start_blk + EXT4_SB(sb)->s_itb_per_group > last_blk)
 272                         goto next_group;
 273                 group_data[it_index].inode_table = start_blk;
 274                 ext4_get_group_no_and_offset(sb, start_blk, &group, NULL);
 275                 group -= group_data[0].group;
 276                 group_data[group].free_blocks_count -=
 277                                         EXT4_SB(sb)->s_itb_per_group;
 278                 if (flexbg_size > 1)
 279                         flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
 280
 281                 start_blk += EXT4_SB(sb)->s_itb_per_group;
 282         }
 283
 284         if (test_opt(sb, DEBUG)) {
 285                 int i;
 286                 group = group_data[0].group;
 287
 288                 printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
 289                        "%d groups, flexbg size is %d:\n", flex_gd->count,
 290                        flexbg_size);
 291
 292                 for (i = 0; i < flex_gd->count; i++) {
 293                         printk(KERN_DEBUG "adding %s group %u: %u "
 294                                "blocks (%d free)\n",
 295                                ext4_bg_has_super(sb, group + i) ? "normal" :
 296                                "no-super", group + i,
 297                                group_data[i].blocks_count,
 298                                group_data[i].free_blocks_count);
 299                 }
 300         }
 301 }
 302
 303 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 304                                   ext4_fsblk_t blk)
 305 {
 306         struct buffer_head *bh;
 307         int err;
 308
 309         bh = sb_getblk(sb, blk);
 310         if (!bh)
 311                 return ERR_PTR(-EIO);
 312         if ((err = ext4_journal_get_write_access(handle, bh))) {
 313                 brelse(bh);
 314                 bh = ERR_PTR(err);
 315         } else {
 316                 memset(bh->b_data, 0, sb->s_blocksize);
 317                 set_buffer_uptodate(bh);
 318         }
 319
 320         return bh;
 321 }
 322
 323 /*
 324  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
 325  * If that fails, restart the transaction & regain write access for the
 326  * buffer head which is used for block_bitmap modifications.
 327  */
 328 static int extend_or_restart_transaction(handle_t *handle, int thresh)
 329 {
 330         int err;
 331
 332         if (ext4_handle_has_enough_credits(handle, thresh))
 333                 return 0;
 334
 335         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
 336         if (err < 0)
 337                 return err;
 338         if (err) {
 339                 err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA);
 340                 if (err)
 341                         return err;
 342         }
 343
 344         return 0;
 345 }
 346
 347 /*
 348  * set_flexbg_block_bitmap() mark @count blocks starting from @block used.
 349  *
 350  * Helper function for ext4_setup_new_group_blocks() which set .
 351  *
 352  * @sb: super block
 353  * @handle: journal handle
 354  * @flex_gd: flex group data
 355  */
 356 static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 357                         struct ext4_new_flex_group_data *flex_gd,
 358                         ext4_fsblk_t block, ext4_group_t count)
 359 {
 360         ext4_group_t count2;
 361
 362         ext4_debug("mark blocks [%llu/%u] used\n", block, count);
 363         for (count2 = count; count > 0; count -= count2, block += count2) {
 364                 ext4_fsblk_t start;
 365                 struct buffer_head *bh;
 366                 ext4_group_t group;
 367                 int err;
 368
 369                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
 370                 start = ext4_group_first_block_no(sb, group);
 371                 group -= flex_gd->groups[0].group;
 372
 373                 count2 = sb->s_blocksize * 8 - (block - start);
 374                 if (count2 > count)
 375                         count2 = count;
 376
 377                 if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
 378                         BUG_ON(flex_gd->count > 1);
 379                         continue;
 380                 }
 381
 382                 err = extend_or_restart_transaction(handle, 1);
 383                 if (err)
 384                         return err;
 385
 386                 bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
 387                 if (!bh)
 388                         return -EIO;
 389
 390                 err = ext4_journal_get_write_access(handle, bh);
 391                 if (err)
 392                         return err;
 393                 ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n", block,
 394                            block - start, count2);
 395                 ext4_set_bits(bh->b_data, block - start, count2);
 396
 397                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 398                 if (unlikely(err))
 399                         return err;
 400                 brelse(bh);
 401         }
 402
 403         return 0;
 404 }
 405
 406 /*
 407  * Set up the block and inode bitmaps, and the inode table for the new groups.
 408  * This doesn't need to be part of the main transaction, since we are only
 409  * changing blocks outside the actual filesystem.  We still do journaling to
 410  * ensure the recovery is correct in case of a failure just after resize.
 411  * If any part of this fails, we simply abort the resize.
 412  *
 413  * setup_new_flex_group_blocks handles a flex group as follow:
 414  *  1. copy super block and GDT, and initialize group tables if necessary.
 415  *     In this step, we only set bits in blocks bitmaps for blocks taken by
 416  *     super block and GDT.
 417  *  2. allocate group tables in block bitmaps, that is, set bits in block
 418  *     bitmap for blocks taken by group tables.
 419  */
 420 static int setup_new_flex_group_blocks(struct super_block *sb,
 421                                 struct ext4_new_flex_group_data *flex_gd)
 422 {
 423         int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
 424         ext4_fsblk_t start;
 425         ext4_fsblk_t block;
 426         struct ext4_sb_info *sbi = EXT4_SB(sb);
 427         struct ext4_super_block *es = sbi->s_es;
 428         struct ext4_new_group_data *group_data = flex_gd->groups;
 429         __u16 *bg_flags = flex_gd->bg_flags;
 430         handle_t *handle;
 431         ext4_group_t group, count;
 432         struct buffer_head *bh = NULL;
 433         int reserved_gdb, i, j, err = 0, err2;
 434
 435         BUG_ON(!flex_gd->count || !group_data ||
 436                group_data[0].group != sbi->s_groups_count);
 437
 438         reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
 439
 440         /* This transaction may be extended/restarted along the way */
 441         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 442         if (IS_ERR(handle))
 443                 return PTR_ERR(handle);
 444
 445         group = group_data[0].group;
 446         for (i = 0; i < flex_gd->count; i++, group++) {
 447                 unsigned long gdblocks;
 448
 449                 gdblocks = ext4_bg_num_gdb(sb, group);
 450                 start = ext4_group_first_block_no(sb, group);
 451
 452                 /* Copy all of the GDT blocks into the backup in this group */
 453                 for (j = 0, block = start + 1; j < gdblocks; j++, block++) {
 454                         struct buffer_head *gdb;
 455
 456                         ext4_debug("update backup group %#04llx\n", block);
 457                         err = extend_or_restart_transaction(handle, 1);
 458                         if (err)
 459                                 goto out;
 460
 461                         gdb = sb_getblk(sb, block);
 462                         if (!gdb) {
 463                                 err = -EIO;
 464                                 goto out;
 465                         }
 466
 467                         err = ext4_journal_get_write_access(handle, gdb);
 468                         if (err) {
 469                                 brelse(gdb);
 470                                 goto out;
 471                         }
 472                         memcpy(gdb->b_data, sbi->s_group_desc[j]->b_data,
 473                                gdb->b_size);
 474                         set_buffer_uptodate(gdb);
 475
 476                         err = ext4_handle_dirty_metadata(handle, NULL, gdb);
 477                         if (unlikely(err)) {
 478                                 brelse(gdb);
 479                                 goto out;
 480                         }
 481                         brelse(gdb);
 482                 }
 483
 484                 /* Zero out all of the reserved backup group descriptor
 485                  * table blocks
 486                  */
 487                 if (ext4_bg_has_super(sb, group)) {
 488                         err = sb_issue_zeroout(sb, gdblocks + start + 1,
 489                                         reserved_gdb, GFP_NOFS);
 490                         if (err)
 491                                 goto out;
 492                 }
 493
 494                 /* Initialize group tables of the grop @group */
 495                 if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
 496                         goto handle_bb;
 497
 498                 /* Zero out all of the inode table blocks */
 499                 block = group_data[i].inode_table;
 500                 ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
 501                            block, sbi->s_itb_per_group);
 502                 err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
 503                                        GFP_NOFS);
 504                 if (err)
 505                         goto out;
 506
 507 handle_bb:
 508                 if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
 509                         goto handle_ib;
 510
 511                 /* Initialize block bitmap of the @group */
 512                 block = group_data[i].block_bitmap;
 513                 err = extend_or_restart_transaction(handle, 1);
 514                 if (err)
 515                         goto out;
 516
 517                 bh = bclean(handle, sb, block);
 518                 if (IS_ERR(bh)) {
 519                         err = PTR_ERR(bh);
 520                         goto out;
 521                 }
 522                 if (ext4_bg_has_super(sb, group)) {
 523                         ext4_debug("mark backup superblock %#04llx (+0)\n",
 524                                    start);
 525                         ext4_set_bits(bh->b_data, 0, gdblocks + reserved_gdb +
 526                                                      1);
 527                 }
 528                 ext4_mark_bitmap_end(group_data[i].blocks_count,
 529                                      sb->s_blocksize * 8, bh->b_data);
 530                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 531                 if (err)
 532                         goto out;
 533                 brelse(bh);
 534
 535 handle_ib:
 536                 if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
 537                         continue;
 538
 539                 /* Initialize inode bitmap of the @group */
 540                 block = group_data[i].inode_bitmap;
 541                 err = extend_or_restart_transaction(handle, 1);
 542                 if (err)
 543                         goto out;
 544                 /* Mark unused entries in inode bitmap used */
 545                 bh = bclean(handle, sb, block);
 546                 if (IS_ERR(bh)) {
 547                         err = PTR_ERR(bh);
 548                         goto out;
 549                 }
 550
 551                 ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
 552                                      sb->s_blocksize * 8, bh->b_data);
 553                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 554                 if (err)
 555                         goto out;
 556                 brelse(bh);
 557         }
 558         bh = NULL;
 559
 560         /* Mark group tables in block bitmap */
 561         for (j = 0; j < GROUP_TABLE_COUNT; j++) {
 562                 count = group_table_count[j];
 563                 start = (&group_data[0].block_bitmap)[j];
 564                 block = start;
 565                 for (i = 1; i < flex_gd->count; i++) {
 566                         block += group_table_count[j];
 567                         if (block == (&group_data[i].block_bitmap)[j]) {
 568                                 count += group_table_count[j];
 569                                 continue;
 570                         }
 571                         err = set_flexbg_block_bitmap(sb, handle,
 572                                                 flex_gd, start, count);
 573                         if (err)
 574                                 goto out;
 575                         count = group_table_count[j];
 576                         start = group_data[i].block_bitmap;
 577                         block = start;
 578                 }
 579
 580                 if (count) {
 581                         err = set_flexbg_block_bitmap(sb, handle,
 582                                                 flex_gd, start, count);
 583                         if (err)
 584                                 goto out;
 585                 }
 586         }
 587
 588 out:
 589         brelse(bh);
 590         err2 = ext4_journal_stop(handle);
 591         if (err2 && !err)
 592                 err = err2;
 593
 594         return err;
 595 }
 596
 597 /*
 598  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
 599  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
 600  * calling this for the first time.  In a sparse filesystem it will be the
 601  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
 602  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
 603  */
 604 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
 605                                   unsigned *five, unsigned *seven)
 606 {
 607         unsigned *min = three;
 608         int mult = 3;
 609         unsigned ret;
 610
 611         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 612                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
 613                 ret = *min;
 614                 *min += 1;
 615                 return ret;
 616         }
 617
 618         if (*five < *min) {
 619                 min = five;
 620                 mult = 5;
 621         }
 622         if (*seven < *min) {
 623                 min = seven;
 624                 mult = 7;
 625         }
 626
 627         ret = *min;
 628         *min *= mult;
 629
 630         return ret;
 631 }
 632
 633 /*
 634  * Check that all of the backup GDT blocks are held in the primary GDT block.
 635  * It is assumed that they are stored in group order.  Returns the number of
 636  * groups in current filesystem that have BACKUPS, or -ve error code.
 637  */
 638 static int verify_reserved_gdb(struct super_block *sb,
 639                                ext4_group_t end,
 640                                struct buffer_head *primary)
 641 {
 642         const ext4_fsblk_t blk = primary->b_blocknr;
 643         unsigned three = 1;
 644         unsigned five = 5;
 645         unsigned seven = 7;
 646         unsigned grp;
 647         __le32 *p = (__le32 *)primary->b_data;
 648         int gdbackups = 0;
 649
 650         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
 651                 if (le32_to_cpu(*p++) !=
 652                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
 653                         ext4_warning(sb, "reserved GDT %llu"
 654                                      " missing grp %d (%llu)",
 655                                      blk, grp,
 656                                      grp *
 657                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 658                                      blk);
 659                         return -EINVAL;
 660                 }
 661                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
 662                         return -EFBIG;
 663         }
 664
 665         return gdbackups;
 666 }
 667
 668 /*
 669  * Called when we need to bring a reserved group descriptor table block into
 670  * use from the resize inode.  The primary copy of the new GDT block currently
 671  * is an indirect block (under the double indirect block in the resize inode).
 672  * The new backup GDT blocks will be stored as leaf blocks in this indirect
 673  * block, in group order.  Even though we know all the block numbers we need,
 674  * we check to ensure that the resize inode has actually reserved these blocks.
 675  *
 676  * Don't need to update the block bitmaps because the blocks are still in use.
 677  *
 678  * We get all of the error cases out of the way, so that we are sure to not
 679  * fail once we start modifying the data on disk, because JBD has no rollback.
 680  */
 681 static int add_new_gdb(handle_t *handle, struct inode *inode,
 682                        ext4_group_t group)
 683 {
 684         struct super_block *sb = inode->i_sb;
 685         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 686         unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
 687         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
 688         struct buffer_head **o_group_desc, **n_group_desc;
 689         struct buffer_head *dind;
 690         struct buffer_head *gdb_bh;
 691         int gdbackups;
 692         struct ext4_iloc iloc;
 693         __le32 *data;
 694         int err;
 695
 696         if (test_opt(sb, DEBUG))
 697                 printk(KERN_DEBUG
 698                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
 699                        gdb_num);
 700
 701         /*
 702          * If we are not using the primary superblock/GDT copy don't resize,
 703          * because the user tools have no way of handling this.  Probably a
 704          * bad time to do it anyways.
 705          */
 706         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
 707             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
 708                 ext4_warning(sb, "won't resize using backup superblock at %llu",
 709                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
 710                 return -EPERM;
 711         }
 712
 713         gdb_bh = sb_bread(sb, gdblock);
 714         if (!gdb_bh)
 715                 return -EIO;
 716
 717         gdbackups = verify_reserved_gdb(sb, group, gdb_bh);
 718         if (gdbackups < 0) {
 719                 err = gdbackups;
 720                 goto exit_bh;
 721         }
 722
 723         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 724         dind = sb_bread(sb, le32_to_cpu(*data));
 725         if (!dind) {
 726                 err = -EIO;
 727                 goto exit_bh;
 728         }
 729
 730         data = (__le32 *)dind->b_data;
 731         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
 732                 ext4_warning(sb, "new group %u GDT block %llu not reserved",
 733                              group, gdblock);
 734                 err = -EINVAL;
 735                 goto exit_dind;
 736         }
 737
 738         err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
 739         if (unlikely(err))
 740                 goto exit_dind;
 741
 742         err = ext4_journal_get_write_access(handle, gdb_bh);
 743         if (unlikely(err))
 744                 goto exit_sbh;
 745
 746         err = ext4_journal_get_write_access(handle, dind);
 747         if (unlikely(err))
 748                 ext4_std_error(sb, err);
 749
 750         /* ext4_reserve_inode_write() gets a reference on the iloc */
 751         err = ext4_reserve_inode_write(handle, inode, &iloc);
 752         if (unlikely(err))
 753                 goto exit_dindj;
 754
 755         n_group_desc = ext4_kvmalloc((gdb_num + 1) *
 756                                      sizeof(struct buffer_head *),
 757                                      GFP_NOFS);
 758         if (!n_group_desc) {
 759                 err = -ENOMEM;
 760                 ext4_warning(sb, "not enough memory for %lu groups",
 761                              gdb_num + 1);
 762                 goto exit_inode;
 763         }
 764
 765         /*
 766          * Finally, we have all of the possible failures behind us...
 767          *
 768          * Remove new GDT block from inode double-indirect block and clear out
 769          * the new GDT block for use (which also "frees" the backup GDT blocks
 770          * from the reserved inode).  We don't need to change the bitmaps for
 771          * these blocks, because they are marked as in-use from being in the
 772          * reserved inode, and will become GDT blocks (primary and backup).
 773          */
 774         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
 775         err = ext4_handle_dirty_metadata(handle, NULL, dind);
 776         if (unlikely(err)) {
 777                 ext4_std_error(sb, err);
 778                 goto exit_inode;
 779         }
 780         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
 781         ext4_mark_iloc_dirty(handle, inode, &iloc);
 782         memset(gdb_bh->b_data, 0, sb->s_blocksize);
 783         err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
 784         if (unlikely(err)) {
 785                 ext4_std_error(sb, err);
 786                 goto exit_inode;
 787         }
 788         brelse(dind);
 789
 790         o_group_desc = EXT4_SB(sb)->s_group_desc;
 791         memcpy(n_group_desc, o_group_desc,
 792                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
 793         n_group_desc[gdb_num] = gdb_bh;
 794         EXT4_SB(sb)->s_group_desc = n_group_desc;
 795         EXT4_SB(sb)->s_gdb_count++;
 796         ext4_kvfree(o_group_desc);
 797
 798         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
 799         err = ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 800         if (err)
 801                 ext4_std_error(sb, err);
 802
 803         return err;
 804
 805 exit_inode:
 806         ext4_kvfree(n_group_desc);
 807         /* ext4_handle_release_buffer(handle, iloc.bh); */
 808         brelse(iloc.bh);
 809 exit_dindj:
 810         /* ext4_handle_release_buffer(handle, dind); */
 811 exit_sbh:
 812         /* ext4_handle_release_buffer(handle, EXT4_SB(sb)->s_sbh); */
 813 exit_dind:
 814         brelse(dind);
 815 exit_bh:
 816         brelse(gdb_bh);
 817
 818         ext4_debug("leaving with error %d\n", err);
 819         return err;
 820 }
 821
 822 /*
 823  * Called when we are adding a new group which has a backup copy of each of
 824  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
 825  * We need to add these reserved backup GDT blocks to the resize inode, so
 826  * that they are kept for future resizing and not allocated to files.
 827  *
 828  * Each reserved backup GDT block will go into a different indirect block.
 829  * The indirect blocks are actually the primary reserved GDT blocks,
 830  * so we know in advance what their block numbers are.  We only get the
 831  * double-indirect block to verify it is pointing to the primary reserved
 832  * GDT blocks so we don't overwrite a data block by accident.  The reserved
 833  * backup GDT blocks are stored in their reserved primary GDT block.
 834  */
 835 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
 836                               ext4_group_t group)
 837 {
 838         struct super_block *sb = inode->i_sb;
 839         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
 840         struct buffer_head **primary;
 841         struct buffer_head *dind;
 842         struct ext4_iloc iloc;
 843         ext4_fsblk_t blk;
 844         __le32 *data, *end;
 845         int gdbackups = 0;
 846         int res, i;
 847         int err;
 848
 849         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
 850         if (!primary)
 851                 return -ENOMEM;
 852
 853         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
 854         dind = sb_bread(sb, le32_to_cpu(*data));
 855         if (!dind) {
 856                 err = -EIO;
 857                 goto exit_free;
 858         }
 859
 860         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
 861         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
 862                                          EXT4_ADDR_PER_BLOCK(sb));
 863         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
 864
 865         /* Get each reserved primary GDT block and verify it holds backups */
 866         for (res = 0; res < reserved_gdb; res++, blk++) {
 867                 if (le32_to_cpu(*data) != blk) {
 868                         ext4_warning(sb, "reserved block %llu"
 869                                      " not at offset %ld",
 870                                      blk,
 871                                      (long)(data - (__le32 *)dind->b_data));
 872                         err = -EINVAL;
 873                         goto exit_bh;
 874                 }
 875                 primary[res] = sb_bread(sb, blk);
 876                 if (!primary[res]) {
 877                         err = -EIO;
 878                         goto exit_bh;
 879                 }
 880                 gdbackups = verify_reserved_gdb(sb, group, primary[res]);
 881                 if (gdbackups < 0) {
 882                         brelse(primary[res]);
 883                         err = gdbackups;
 884                         goto exit_bh;
 885                 }
 886                 if (++data >= end)
 887                         data = (__le32 *)dind->b_data;
 888         }
 889
 890         for (i = 0; i < reserved_gdb; i++) {
 891                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
 892                         /*
 893                         int j;
 894                         for (j = 0; j < i; j++)
 895                                 ext4_handle_release_buffer(handle, primary[j]);
 896                          */
 897                         goto exit_bh;
 898                 }
 899         }
 900
 901         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
 902                 goto exit_bh;
 903
 904         /*
 905          * Finally we can add each of the reserved backup GDT blocks from
 906          * the new group to its reserved primary GDT block.
 907          */
 908         blk = group * EXT4_BLOCKS_PER_GROUP(sb);
 909         for (i = 0; i < reserved_gdb; i++) {
 910                 int err2;
 911                 data = (__le32 *)primary[i]->b_data;
 912                 /* printk("reserving backup %lu[%u] = %lu\n",
 913                        primary[i]->b_blocknr, gdbackups,
 914                        blk + primary[i]->b_blocknr); */
 915                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
 916                 err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
 917                 if (!err)
 918                         err = err2;
 919         }
 920         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
 921         ext4_mark_iloc_dirty(handle, inode, &iloc);
 922
 923 exit_bh:
 924         while (--res >= 0)
 925                 brelse(primary[res]);
 926         brelse(dind);
 927
 928 exit_free:
 929         kfree(primary);
 930
 931         return err;
 932 }
 933
 934 /*
 935  * Update the backup copies of the ext4 metadata.  These don't need to be part
 936  * of the main resize transaction, because e2fsck will re-write them if there
 937  * is a problem (basically only OOM will cause a problem).  However, we
 938  * _should_ update the backups if possible, in case the primary gets trashed
 939  * for some reason and we need to run e2fsck from a backup superblock.  The
 940  * important part is that the new block and inode counts are in the backup
 941  * superblocks, and the location of the new group metadata in the GDT backups.
 942  *
 943  * We do not need take the s_resize_lock for this, because these
 944  * blocks are not otherwise touched by the filesystem code when it is
 945  * mounted.  We don't need to worry about last changing from
 946  * sbi->s_groups_count, because the worst that can happen is that we
 947  * do not copy the full number of backups at this time.  The resize
 948  * which changed s_groups_count will backup again.
 949  */
 950 static void update_backups(struct super_block *sb,
 951                            int blk_off, char *data, int size)
 952 {
 953         struct ext4_sb_info *sbi = EXT4_SB(sb);
 954         const ext4_group_t last = sbi->s_groups_count;
 955         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
 956         unsigned three = 1;
 957         unsigned five = 5;
 958         unsigned seven = 7;
 959         ext4_group_t group;
 960         int rest = sb->s_blocksize - size;
 961         handle_t *handle;
 962         int err = 0, err2;
 963
 964         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
 965         if (IS_ERR(handle)) {
 966                 group = 1;
 967                 err = PTR_ERR(handle);
 968                 goto exit_err;
 969         }
 970
 971         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
 972                 struct buffer_head *bh;
 973
 974                 /* Out of journal space, and can't get more - abort - so sad */
 975                 if (ext4_handle_valid(handle) &&
 976                     handle->h_buffer_credits == 0 &&
 977                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
 978                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
 979                         break;
 980
 981                 bh = sb_getblk(sb, group * bpg + blk_off);
 982                 if (!bh) {
 983                         err = -EIO;
 984                         break;
 985                 }
 986                 ext4_debug("update metadata backup %#04lx\n",
 987                           (unsigned long)bh->b_blocknr);
 988                 if ((err = ext4_journal_get_write_access(handle, bh)))
 989                         break;
 990                 lock_buffer(bh);
 991                 memcpy(bh->b_data, data, size);
 992                 if (rest)
 993                         memset(bh->b_data + size, 0, rest);
 994                 set_buffer_uptodate(bh);
 995                 unlock_buffer(bh);
 996                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
 997                 if (unlikely(err))
 998                         ext4_std_error(sb, err);
 999                 brelse(bh);
1000         }
1001         if ((err2 = ext4_journal_stop(handle)) && !err)
1002                 err = err2;
1003
1004         /*
1005          * Ugh! Need to have e2fsck write the backup copies.  It is too
1006          * late to revert the resize, we shouldn't fail just because of
1007          * the backup copies (they are only needed in case of corruption).
1008          *
1009          * However, if we got here we have a journal problem too, so we
1010          * can't really start a transaction to mark the superblock.
1011          * Chicken out and just set the flag on the hope it will be written
1012          * to disk, and if not - we will simply wait until next fsck.
1013          */
1014 exit_err:
1015         if (err) {
1016                 ext4_warning(sb, "can't update backup for group %u (err %d), "
1017                              "forcing fsck on next reboot", group, err);
1018                 sbi->s_mount_state &= ~EXT4_VALID_FS;
1019                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
1020                 mark_buffer_dirty(sbi->s_sbh);
1021         }
1022 }
1023
1024 /*
1025  * ext4_add_new_descs() adds @count group descriptor of groups
1026  * starting at @group
1027  *
1028  * @handle: journal handle
1029  * @sb: super block
1030  * @group: the group no. of the first group desc to be added
1031  * @resize_inode: the resize inode
1032  * @count: number of group descriptors to be added
1033  */
1034 static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
1035                               ext4_group_t group, struct inode *resize_inode,
1036                               ext4_group_t count)
1037 {
1038         struct ext4_sb_info *sbi = EXT4_SB(sb);
1039         struct ext4_super_block *es = sbi->s_es;
1040         struct buffer_head *gdb_bh;
1041         int i, gdb_off, gdb_num, err = 0;
1042
1043         for (i = 0; i < count; i++, group++) {
1044                 int reserved_gdb = ext4_bg_has_super(sb, group) ?
1045                         le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1046
1047                 gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1048                 gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1049
1050                 /*
1051                  * We will only either add reserved group blocks to a backup group
1052                  * or remove reserved blocks for the first group in a new group block.
1053                  * Doing both would be mean more complex code, and sane people don't
1054                  * use non-sparse filesystems anymore.  This is already checked above.
1055                  */
1056                 if (gdb_off) {
1057                         gdb_bh = sbi->s_group_desc[gdb_num];
1058                         err = ext4_journal_get_write_access(handle, gdb_bh);
1059
1060                         if (!err && reserved_gdb && ext4_bg_num_gdb(sb, group))
1061                                 err = reserve_backup_gdb(handle, resize_inode, group);
1062                 } else
1063                         err = add_new_gdb(handle, resize_inode, group);
1064                 if (err)
1065                         break;
1066         }
1067         return err;
1068 }
1069
1070 /*
1071  * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
1072  */
1073 static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
1074                                 struct ext4_new_flex_group_data *flex_gd)
1075 {
1076         struct ext4_new_group_data      *group_data = flex_gd->groups;
1077         struct ext4_group_desc          *gdp;
1078         struct ext4_sb_info             *sbi = EXT4_SB(sb);
1079         struct buffer_head              *gdb_bh;
1080         ext4_group_t                    group;
1081         __u16                           *bg_flags = flex_gd->bg_flags;
1082         int                             i, gdb_off, gdb_num, err = 0;
1083
1084
1085         for (i = 0; i < flex_gd->count; i++, group_data++, bg_flags++) {
1086                 group = group_data->group;
1087
1088                 gdb_off = group % EXT4_DESC_PER_BLOCK(sb);
1089                 gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
1090
1091                 /*
1092                  * get_write_access() has been called on gdb_bh by ext4_add_new_desc().
1093                  */
1094                 gdb_bh = sbi->s_group_desc[gdb_num];
1095                 /* Update group descriptor block for new group */
1096                 gdp = (struct ext4_group_desc *)((char *)gdb_bh->b_data +
1097                                                  gdb_off * EXT4_DESC_SIZE(sb));
1098
1099                 memset(gdp, 0, EXT4_DESC_SIZE(sb));
1100                 ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
1101                 ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
1102                 ext4_inode_table_set(sb, gdp, group_data->inode_table);
1103                 ext4_free_group_clusters_set(sb, gdp,
1104                                              EXT4_B2C(sbi, group_data->free_blocks_count));
1105                 ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
1106                 gdp->bg_flags = cpu_to_le16(*bg_flags);
1107                 gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
1108
1109                 err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
1110                 if (unlikely(err)) {
1111                         ext4_std_error(sb, err);
1112                         break;
1113                 }
1114
1115                 /*
1116                  * We can allocate memory for mb_alloc based on the new group
1117                  * descriptor
1118                  */
1119                 err = ext4_mb_add_groupinfo(sb, group, gdp);
1120                 if (err)
1121                         break;
1122         }
1123         return err;
1124 }
1125
1126 /*
1127  * ext4_update_super() updates the super block so that the newly added
1128  * groups can be seen by the filesystem.
1129  *
1130  * @sb: super block
1131  * @flex_gd: new added groups
1132  */
1133 static void ext4_update_super(struct super_block *sb,
1134                              struct ext4_new_flex_group_data *flex_gd)
1135 {
1136         ext4_fsblk_t blocks_count = 0;
1137         ext4_fsblk_t free_blocks = 0;
1138         ext4_fsblk_t reserved_blocks = 0;
1139         struct ext4_new_group_data *group_data = flex_gd->groups;
1140         struct ext4_sb_info *sbi = EXT4_SB(sb);
1141         struct ext4_super_block *es = sbi->s_es;
1142         int i;
1143
1144         BUG_ON(flex_gd->count == 0 || group_data == NULL);
1145         /*
1146          * Make the new blocks and inodes valid next.  We do this before
1147          * increasing the group count so that once the group is enabled,
1148          * all of its blocks and inodes are already valid.
1149          *
1150          * We always allocate group-by-group, then block-by-block or
1151          * inode-by-inode within a group, so enabling these
1152          * blocks/inodes before the group is live won't actually let us
1153          * allocate the new space yet.
1154          */
1155         for (i = 0; i < flex_gd->count; i++) {
1156                 blocks_count += group_data[i].blocks_count;
1157                 free_blocks += group_data[i].free_blocks_count;
1158         }
1159
1160         reserved_blocks = ext4_r_blocks_count(es) * 100;
1161         do_div(reserved_blocks, ext4_blocks_count(es));
1162         reserved_blocks *= blocks_count;
1163         do_div(reserved_blocks, 100);
1164
1165         ext4_blocks_count_set(es, ext4_blocks_count(es) + blocks_count);
1166         ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + free_blocks);
1167         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1168                      flex_gd->count);
1169         le32_add_cpu(&es->s_free_inodes_count, EXT4_INODES_PER_GROUP(sb) *
1170                      flex_gd->count);
1171
1172         /*
1173          * We need to protect s_groups_count against other CPUs seeing
1174          * inconsistent state in the superblock.
1175          *
1176          * The precise rules we use are:
1177          *
1178          * * Writers must perform a smp_wmb() after updating all
1179          *   dependent data and before modifying the groups count
1180          *
1181          * * Readers must perform an smp_rmb() after reading the groups
1182          *   count and before reading any dependent data.
1183          *
1184          * NB. These rules can be relaxed when checking the group count
1185          * while freeing data, as we can only allocate from a block
1186          * group after serialising against the group count, and we can
1187          * only then free after serialising in turn against that
1188          * allocation.
1189          */
1190         smp_wmb();
1191
1192         /* Update the global fs size fields */
1193         sbi->s_groups_count += flex_gd->count;
1194
1195         /* Update the reserved block counts only once the new group is
1196          * active. */
1197         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
1198                                 reserved_blocks);
1199
1200         /* Update the free space counts */
1201         percpu_counter_add(&sbi->s_freeclusters_counter,
1202                            EXT4_B2C(sbi, free_blocks));
1203         percpu_counter_add(&sbi->s_freeinodes_counter,
1204                            EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
1205
1206         if (EXT4_HAS_INCOMPAT_FEATURE(sb,
1207                                       EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
1208             sbi->s_log_groups_per_flex) {
1209                 ext4_group_t flex_group;
1210                 flex_group = ext4_flex_group(sbi, group_data[0].group);
1211                 atomic_add(EXT4_B2C(sbi, free_blocks),
1212                            &sbi->s_flex_groups[flex_group].free_clusters);
1213                 atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
1214                            &sbi->s_flex_groups[flex_group].free_inodes);
1215         }
1216
1217         if (test_opt(sb, DEBUG))
1218                 printk(KERN_DEBUG "EXT4-fs: added group %u:"
1219                        "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,
1220                        blocks_count, free_blocks, reserved_blocks);
1221 }
1222
1223 /* Add a flex group to an fs. Ensure we handle all possible error conditions
1224  * _before_ we start modifying the filesystem, because we cannot abort the
1225  * transaction and not have it write the data to disk.
1226  */
1227 static int ext4_flex_group_add(struct super_block *sb,
1228                                struct inode *resize_inode,
1229                                struct ext4_new_flex_group_data *flex_gd)
1230 {
1231         struct ext4_sb_info *sbi = EXT4_SB(sb);
1232         struct ext4_super_block *es = sbi->s_es;
1233         ext4_fsblk_t o_blocks_count;
1234         ext4_grpblk_t last;
1235         ext4_group_t group;
1236         handle_t *handle;
1237         unsigned reserved_gdb;
1238         int err = 0, err2 = 0, credit;
1239
1240         BUG_ON(!flex_gd->count || !flex_gd->groups || !flex_gd->bg_flags);
1241
1242         reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
1243         o_blocks_count = ext4_blocks_count(es);
1244         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1245         BUG_ON(last);
1246
1247         err = setup_new_flex_group_blocks(sb, flex_gd);
1248         if (err)
1249                 goto exit;
1250         /*
1251          * We will always be modifying at least the superblock and  GDT
1252          * block.  If we are adding a group past the last current GDT block,
1253          * we will also modify the inode and the dindirect block.  If we
1254          * are adding a group with superblock/GDT backups  we will also
1255          * modify each of the reserved GDT dindirect blocks.
1256          */
1257         credit = flex_gd->count * 4 + reserved_gdb;
1258         handle = ext4_journal_start_sb(sb, credit);
1259         if (IS_ERR(handle)) {
1260                 err = PTR_ERR(handle);
1261                 goto exit;
1262         }
1263
1264         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
1265         if (err)
1266                 goto exit_journal;
1267
1268         group = flex_gd->groups[0].group;
1269         BUG_ON(group != EXT4_SB(sb)->s_groups_count);
1270         err = ext4_add_new_descs(handle, sb, group,
1271                                 resize_inode, flex_gd->count);
1272         if (err)
1273                 goto exit_journal;
1274
1275         err = ext4_setup_new_descs(handle, sb, flex_gd);
1276         if (err)
1277                 goto exit_journal;
1278
1279         ext4_update_super(sb, flex_gd);
1280
1281         err = ext4_handle_dirty_super(handle, sb);
1282
1283 exit_journal:
1284         err2 = ext4_journal_stop(handle);
1285         if (!err)
1286                 err = err2;
1287
1288         if (!err) {
1289                 int i;
1290                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
1291                                sizeof(struct ext4_super_block));
1292                 for (i = 0; i < flex_gd->count; i++, group++) {
1293                         struct buffer_head *gdb_bh;
1294                         int gdb_num;
1295                         gdb_num = group / EXT4_BLOCKS_PER_GROUP(sb);
1296                         gdb_bh = sbi->s_group_desc[gdb_num];
1297                         update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
1298                                        gdb_bh->b_size);
1299                 }
1300         }
1301 exit:
1302         return err;
1303 }
1304
1305 static int ext4_setup_next_flex_gd(struct super_block *sb,
1306                                     struct ext4_new_flex_group_data *flex_gd,
1307                                     ext4_fsblk_t n_blocks_count,
1308                                     unsigned long flexbg_size)
1309 {
1310         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1311         struct ext4_new_group_data *group_data = flex_gd->groups;
1312         ext4_fsblk_t o_blocks_count;
1313         ext4_group_t n_group;
1314         ext4_group_t group;
1315         ext4_group_t last_group;
1316         ext4_grpblk_t last;
1317         ext4_grpblk_t blocks_per_group;
1318         unsigned long i;
1319
1320         blocks_per_group = EXT4_BLOCKS_PER_GROUP(sb);
1321
1322         o_blocks_count = ext4_blocks_count(es);
1323
1324         if (o_blocks_count == n_blocks_count)
1325                 return 0;
1326
1327         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1328         BUG_ON(last);
1329         ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
1330
1331         last_group = group | (flexbg_size - 1);
1332         if (last_group > n_group)
1333                 last_group = n_group;
1334
1335         flex_gd->count = last_group - group + 1;
1336
1337         for (i = 0; i < flex_gd->count; i++) {
1338                 int overhead;
1339
1340                 group_data[i].group = group + i;
1341                 group_data[i].blocks_count = blocks_per_group;
1342                 overhead = ext4_bg_has_super(sb, group + i) ?
1343                            (1 + ext4_bg_num_gdb(sb, group + i) +
1344                             le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
1345                 group_data[i].free_blocks_count = blocks_per_group - overhead;
1346                 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
1347                                                EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
1348                         flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
1349                                                EXT4_BG_INODE_UNINIT;
1350                 else
1351                         flex_gd->bg_flags[i] = EXT4_BG_INODE_ZEROED;
1352         }
1353
1354         if (last_group == n_group &&
1355             EXT4_HAS_RO_COMPAT_FEATURE(sb,
1356                                        EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
1357                 /* We need to initialize block bitmap of last group. */
1358                 flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
1359
1360         if ((last_group == n_group) && (last != blocks_per_group - 1)) {
1361                 group_data[i - 1].blocks_count = last + 1;
1362                 group_data[i - 1].free_blocks_count -= blocks_per_group-
1363                                         last - 1;
1364         }
1365
1366         return 1;
1367 }
1368
1369 /* Add group descriptor data to an existing or new group descriptor block.
1370  * Ensure we handle all possible error conditions _before_ we start modifying
1371  * the filesystem, because we cannot abort the transaction and not have it
1372  * write the data to disk.
1373  *
1374  * If we are on a GDT block boundary, we need to get the reserved GDT block.
1375  * Otherwise, we may need to add backup GDT blocks for a sparse group.
1376  *
1377  * We only need to hold the superblock lock while we are actually adding
1378  * in the new group's counts to the superblock.  Prior to that we have
1379  * not really "added" the group at all.  We re-check that we are still
1380  * adding in the last group in case things have changed since verifying.
1381  */
1382 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
1383 {
1384         struct ext4_new_flex_group_data flex_gd;
1385         struct ext4_sb_info *sbi = EXT4_SB(sb);
1386         struct ext4_super_block *es = sbi->s_es;
1387         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
1388                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
1389         struct inode *inode = NULL;
1390         int gdb_off, gdb_num;
1391         int err;
1392         __u16 bg_flags = 0;
1393
1394         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
1395         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
1396
1397         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
1398                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
1399                 ext4_warning(sb, "Can't resize non-sparse filesystem further");
1400                 return -EPERM;
1401         }
1402
1403         if (ext4_blocks_count(es) + input->blocks_count <
1404             ext4_blocks_count(es)) {
1405                 ext4_warning(sb, "blocks_count overflow");
1406                 return -EINVAL;
1407         }
1408
1409         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
1410             le32_to_cpu(es->s_inodes_count)) {
1411                 ext4_warning(sb, "inodes_count overflow");
1412                 return -EINVAL;
1413         }
1414
1415         if (reserved_gdb || gdb_off == 0) {
1416                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
1417                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)
1418                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
1419                         ext4_warning(sb,
1420                                      "No reserved GDT blocks, can't resize");
1421                         return -EPERM;
1422                 }
1423                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
1424                 if (IS_ERR(inode)) {
1425                         ext4_warning(sb, "Error opening resize inode");
1426                         return PTR_ERR(inode);
1427                 }
1428         }
1429
1430
1431         err = verify_group_input(sb, input);
1432         if (err)
1433                 goto out;
1434
1435         flex_gd.count = 1;
1436         flex_gd.groups = input;
1437         flex_gd.bg_flags = &bg_flags;
1438         err = ext4_flex_group_add(sb, inode, &flex_gd);
1439 out:
1440         iput(inode);
1441         return err;
1442 } /* ext4_group_add */
1443
1444 /*
1445  * extend a group without checking assuming that checking has been done.
1446  */
1447 static int ext4_group_extend_no_check(struct super_block *sb,
1448                                       ext4_fsblk_t o_blocks_count, ext4_grpblk_t add)
1449 {
1450         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
1451         handle_t *handle;
1452         int err = 0, err2;
1453
1454         /* We will update the superblock, one block bitmap, and
1455          * one group descriptor via ext4_group_add_blocks().
1456          */
1457         handle = ext4_journal_start_sb(sb, 3);
1458         if (IS_ERR(handle)) {
1459                 err = PTR_ERR(handle);
1460                 ext4_warning(sb, "error %d on journal start", err);
1461                 return err;
1462         }
1463
1464         err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
1465         if (err) {
1466                 ext4_warning(sb, "error %d on journal write access", err);
1467                 goto errout;
1468         }
1469
1470         ext4_blocks_count_set(es, o_blocks_count + add);
1471         ext4_free_blocks_count_set(es, ext4_free_blocks_count(es) + add);
1472         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1473                    o_blocks_count + add);
1474         /* We add the blocks to the bitmap and set the group need init bit */
1475         err = ext4_group_add_blocks(handle, sb, o_blocks_count, add);
1476         if (err)
1477                 goto errout;
1478         ext4_handle_dirty_super(handle, sb);
1479         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1480                    o_blocks_count + add);
1481 errout:
1482         err2 = ext4_journal_stop(handle);
1483         if (err2 && !err)
1484                 err = err2;
1485
1486         if (!err) {
1487                 if (test_opt(sb, DEBUG))
1488                         printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
1489                                "blocks\n", ext4_blocks_count(es));
1490                 update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1491                                sizeof(struct ext4_super_block));
1492         }
1493         return err;
1494 }
1495
1496 /*
1497  * Extend the filesystem to the new number of blocks specified.  This entry
1498  * point is only used to extend the current filesystem to the end of the last
1499  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
1500  * for emergencies (because it has no dependencies on reserved blocks).
1501  *
1502  * If we _really_ wanted, we could use default values to call ext4_group_add()
1503  * allow the "remount" trick to work for arbitrary resizing, assuming enough
1504  * GDT blocks are reserved to grow to the desired size.
1505  */
1506 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1507                       ext4_fsblk_t n_blocks_count)
1508 {
1509         ext4_fsblk_t o_blocks_count;
1510         ext4_grpblk_t last;
1511         ext4_grpblk_t add;
1512         struct buffer_head *bh;
1513         int err;
1514         ext4_group_t group;
1515
1516         o_blocks_count = ext4_blocks_count(es);
1517
1518         if (test_opt(sb, DEBUG))
1519                 ext4_msg(sb, KERN_DEBUG,
1520                          "extending last group from %llu to %llu blocks",
1521                          o_blocks_count, n_blocks_count);
1522
1523         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
1524                 return 0;
1525
1526         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1527                 ext4_msg(sb, KERN_ERR,
1528                          "filesystem too large to resize to %llu blocks safely",
1529                          n_blocks_count);
1530                 if (sizeof(sector_t) < 8)
1531                         ext4_warning(sb, "CONFIG_LBDAF not enabled");
1532                 return -EINVAL;
1533         }
1534
1535         if (n_blocks_count < o_blocks_count) {
1536                 ext4_warning(sb, "can't shrink FS - resize aborted");
1537                 return -EINVAL;
1538         }
1539
1540         /* Handle the remaining blocks in the last group only. */
1541         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1542
1543         if (last == 0) {
1544                 ext4_warning(sb, "need to use ext2online to resize further");
1545                 return -EPERM;
1546         }
1547
1548         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1549
1550         if (o_blocks_count + add < o_blocks_count) {
1551                 ext4_warning(sb, "blocks_count overflow");
1552                 return -EINVAL;
1553         }
1554
1555         if (o_blocks_count + add > n_blocks_count)
1556                 add = n_blocks_count - o_blocks_count;
1557
1558         if (o_blocks_count + add < n_blocks_count)
1559                 ext4_warning(sb, "will only finish group (%llu blocks, %u new)",
1560                              o_blocks_count + add, add);
1561
1562         /* See if the device is actually as big as what was requested */
1563         bh = sb_bread(sb, o_blocks_count + add - 1);
1564         if (!bh) {
1565                 ext4_warning(sb, "can't read last block, resize aborted");
1566                 return -ENOSPC;
1567         }
1568         brelse(bh);
1569
1570         err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1571         return err;
1572 } /* ext4_group_extend */
1573
1574 /*
1575  * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
1576  *
1577  * @sb: super block of the fs to be resized
1578  * @n_blocks_count: the number of blocks resides in the resized fs
1579  */
1580 int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
1581 {
1582         struct ext4_new_flex_group_data *flex_gd = NULL;
1583         struct ext4_sb_info *sbi = EXT4_SB(sb);
1584         struct ext4_super_block *es = sbi->s_es;
1585         struct buffer_head *bh;
1586         struct inode *resize_inode;
1587         ext4_fsblk_t o_blocks_count;
1588         ext4_group_t o_group;
1589         ext4_group_t n_group;
1590         ext4_grpblk_t offset, add;
1591         unsigned long n_desc_blocks;
1592         unsigned long o_desc_blocks;
1593         unsigned long desc_blocks;
1594         int err = 0, flexbg_size = 1;
1595
1596         o_blocks_count = ext4_blocks_count(es);
1597
1598         if (test_opt(sb, DEBUG))
1599                 ext4_msg(sb, KERN_DEBUG, "resizing filesystem from %llu "
1600                        "to %llu blocks", o_blocks_count, n_blocks_count);
1601
1602         if (n_blocks_count < o_blocks_count) {
1603                 /* On-line shrinking not supported */
1604                 ext4_warning(sb, "can't shrink FS - resize aborted");
1605                 return -EINVAL;
1606         }
1607
1608         if (n_blocks_count == o_blocks_count)
1609                 /* Nothing need to do */
1610                 return 0;
1611
1612         ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &offset);
1613         ext4_get_group_no_and_offset(sb, o_blocks_count - 1, &o_group, &offset);
1614
1615         n_desc_blocks = (n_group + EXT4_DESC_PER_BLOCK(sb)) /
1616                         EXT4_DESC_PER_BLOCK(sb);
1617         o_desc_blocks = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
1618                         EXT4_DESC_PER_BLOCK(sb);
1619         desc_blocks = n_desc_blocks - o_desc_blocks;
1620
1621         if (desc_blocks &&
1622             (!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_RESIZE_INODE) ||
1623              le16_to_cpu(es->s_reserved_gdt_blocks) < desc_blocks)) {
1624                 ext4_warning(sb, "No reserved GDT blocks, can't resize");
1625                 return -EPERM;
1626         }
1627
1628         resize_inode = ext4_iget(sb, EXT4_RESIZE_INO);
1629         if (IS_ERR(resize_inode)) {
1630                 ext4_warning(sb, "Error opening resize inode");
1631                 return PTR_ERR(resize_inode);
1632         }
1633
1634         /* See if the device is actually as big as what was requested */
1635         bh = sb_bread(sb, n_blocks_count - 1);
1636         if (!bh) {
1637                 ext4_warning(sb, "can't read last block, resize aborted");
1638                 return -ENOSPC;
1639         }
1640         brelse(bh);
1641
1642         /* extend the last group */
1643         if (n_group == o_group)
1644                 add = n_blocks_count - o_blocks_count;
1645         else
1646                 add = EXT4_BLOCKS_PER_GROUP(sb) - (offset + 1);
1647         if (add > 0) {
1648                 err = ext4_group_extend_no_check(sb, o_blocks_count, add);
1649                 if (err)
1650                         goto out;
1651         }
1652
1653         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
1654             es->s_log_groups_per_flex)
1655                 flexbg_size = 1 << es->s_log_groups_per_flex;
1656
1657         o_blocks_count = ext4_blocks_count(es);
1658         if (o_blocks_count == n_blocks_count)
1659                 goto out;
1660
1661         flex_gd = alloc_flex_gd(flexbg_size);
1662         if (flex_gd == NULL) {
1663                 err = -ENOMEM;
1664                 goto out;
1665         }
1666
1667         /* Add flex groups. Note that a regular group is a
1668          * flex group with 1 group.
1669          */
1670         while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
1671                                               flexbg_size)) {
1672                 ext4_alloc_group_tables(sb, flex_gd, flexbg_size);
1673                 err = ext4_flex_group_add(sb, resize_inode, flex_gd);
1674                 if (unlikely(err))
1675                         break;
1676         }
1677
1678 out:
1679         if (flex_gd)
1680                 free_flex_gd(flex_gd);
1681
1682         iput(resize_inode);
1683         if (test_opt(sb, DEBUG))
1684                 ext4_msg(sb, KERN_DEBUG, "resized filesystem from %llu "
1685                        "upto %llu blocks", o_blocks_count, n_blocks_count);
1686         return err;
1687 }