uint32_t ext4_num_base_meta_clusters(struct ext4_sblock *s, uint32_t block_group) { uint32_t num; uint32_t dsc_per_block = ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s); num = ext4_sb_is_super_in_bg(s, block_group); if (!ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG) || block_group < ext4_sb_first_meta_bg(s) * dsc_per_block) { if (num) { num += ext4_bg_num_gdb(s, block_group); num += ext4_get16(s, s_reserved_gdt_blocks); } } else { num += ext4_bg_num_gdb(s, block_group); } uint32_t clustersize = 1024 << ext4_get32(s, log_cluster_size); uint32_t cluster_ratio = clustersize / ext4_sb_get_block_size(s); uint32_t v = (num + cluster_ratio - 1) >> ext4_get32(s, log_cluster_size); return v; }
int ext4_setup_system_zone(struct super_block *sb) { ext4_group_t ngroups = ext4_get_groups_count(sb); struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_group_desc *gdp; ext4_group_t i; int flex_size = ext4_flex_bg_size(sbi); int ret; if (!test_opt(sb, BLOCK_VALIDITY)) { if (EXT4_SB(sb)->system_blks.rb_node) ext4_release_system_zone(sb); return 0; } if (EXT4_SB(sb)->system_blks.rb_node) return 0; for (i=0; i < ngroups; i++) { if (ext4_bg_has_super(sb, i) && ((i < 5) || ((i % flex_size) == 0))) add_system_zone(sbi, ext4_group_first_block_no(sb, i), ext4_bg_num_gdb(sb, i) + 1); gdp = ext4_get_group_desc(sb, i, NULL); ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1); if (ret) return ret; ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1); if (ret) return ret; ret = add_system_zone(sbi, ext4_inode_table(sb, gdp), sbi->s_itb_per_group); if (ret) return ret; } if (test_opt(sb, DEBUG)) debug_print_tree(EXT4_SB(sb)); return 0; }
/* Initializes an uninitialized block bitmap if given, and returns the * number of blocks free in the group. */ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, ext4_group_t block_group, struct ext4_group_desc *gdp) { int bit, bit_max; ext4_group_t ngroups = ext4_get_groups_count(sb); unsigned free_blocks, group_blocks; struct ext4_sb_info *sbi = EXT4_SB(sb); if (bh) { J_ASSERT_BH(bh, buffer_locked(bh)); /* If checksum is bad mark all blocks used to prevent allocation * essentially implementing a per-group read-only flag. */ if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) { ext4_error(sb, __func__, "Checksum bad for group %u", block_group); ext4_free_blks_set(sb, gdp, 0); ext4_free_inodes_set(sb, gdp, 0); ext4_itable_unused_set(sb, gdp, 0); memset(bh->b_data, 0xff, sb->s_blocksize); return 0; } memset(bh->b_data, 0, sb->s_blocksize); } /* Check for superblock and gdt backups in this group */ bit_max = ext4_bg_has_super(sb, block_group); if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) || block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * sbi->s_desc_per_block) { if (bit_max) { bit_max += ext4_bg_num_gdb(sb, block_group); bit_max += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); } } else { /* For META_BG_BLOCK_GROUPS */ bit_max += ext4_bg_num_gdb(sb, block_group); } if (block_group == ngroups - 1) { /* * Even though mke2fs always initialize first and last group * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need * to make sure we calculate the right free blocks */ group_blocks = ext4_blocks_count(sbi->s_es) - le32_to_cpu(sbi->s_es->s_first_data_block) - (EXT4_BLOCKS_PER_GROUP(sb) * (ngroups - 1)); } else { group_blocks = EXT4_BLOCKS_PER_GROUP(sb); } free_blocks = group_blocks - bit_max; if (bh) { ext4_fsblk_t start, tmp; int flex_bg = 0; for (bit = 0; bit < bit_max; bit++) ext4_set_bit(bit, bh->b_data); start = ext4_group_first_block_no(sb, block_group); if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) flex_bg = 1; /* Set bits for block and inode bitmaps, and inode table */ tmp = ext4_block_bitmap(sb, gdp); if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); tmp = ext4_inode_bitmap(sb, gdp); if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); tmp = ext4_inode_table(sb, gdp); for (; tmp < ext4_inode_table(sb, gdp) + sbi->s_itb_per_group; tmp++) { if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(tmp - start, bh->b_data); } /* * Also if the number of blocks within the group is * less than the blocksize * 8 ( which is the size * of bitmap ), set rest of the block bitmap to 1 */ mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data); } return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp); }