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;
}
bool ext4_sb_check(struct ext4_sblock *s)
{
if (ext4_get16(s, magic) != EXT4_SUPERBLOCK_MAGIC)
return false;
if (ext4_get32(s, inodes_count) == 0)
return false;
if (ext4_sb_get_blocks_cnt(s) == 0)
return false;
if (ext4_get32(s, blocks_per_group) == 0)
return false;
if (ext4_get32(s, inodes_per_group) == 0)
return false;
if (ext4_get16(s, inode_size) < 128)
return false;
if (ext4_get32(s, first_inode) < 11)
return false;
if (ext4_sb_get_desc_size(s) < EXT4_MIN_BLOCK_GROUP_DESCRIPTOR_SIZE)
return false;
if (ext4_sb_get_desc_size(s) > EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
return false;
if (!ext4_sb_verify_csum(s))
return false;
return true;
}
/**@brief Compute number of block group from block address.
* @param sb superblock pointer.
* @param baddr Absolute address of block.
* @return Block group index
*/
uint32_t ext4_balloc_get_bgid_of_block(struct ext4_sblock *s,
uint64_t baddr)
{
if (ext4_get32(s, first_data_block) && baddr)
baddr--;
return baddr / ext4_get32(s, blocks_per_group);
}
/**@brief Compute the starting block address of a block group
* @param sb superblock pointer.
* @param bgid block group index
* @return Block address
*/
uint64_t ext4_balloc_get_block_of_bgid(struct ext4_sblock *s,
uint32_t bgid)
{
uint64_t baddr = 0;
if (ext4_get32(s, first_data_block))
baddr++;
baddr += bgid * ext4_get32(s, blocks_per_group);
return baddr;
}
uint32_t ext4_inodes_in_group_cnt(struct ext4_sblock *s, uint32_t bgid)
{
uint32_t block_group_count = ext4_block_group_cnt(s);
uint32_t inodes_per_group = ext4_get32(s, inodes_per_group);
uint32_t total_inodes = ext4_get32(s, inodes_count);
if (bgid < block_group_count - 1)
return inodes_per_group;
return (total_inodes - ((block_group_count - 1) * inodes_per_group));
}
uint32_t ext4_blocks_in_group_cnt(struct ext4_sblock *s, uint32_t bgid)
{
uint32_t block_group_count = ext4_block_group_cnt(s);
uint32_t blocks_per_group = ext4_get32(s, blocks_per_group);
uint64_t total_blocks = ext4_sb_get_blocks_cnt(s);
if (bgid < block_group_count - 1)
return blocks_per_group;
return (uint32_t)(total_blocks - ((block_group_count - 1) * blocks_per_group));
}
uint32_t ext4_block_group_cnt(struct ext4_sblock *s)
{
uint64_t blocks_count = ext4_sb_get_blocks_cnt(s);
uint32_t blocks_per_group = ext4_get32(s, blocks_per_group);
uint32_t block_groups_count = (uint32_t)(blocks_count / blocks_per_group);
if (blocks_count % blocks_per_group)
block_groups_count++;
return block_groups_count;
}
static uint32_t ext4_balloc_bitmap_csum(struct ext4_sblock *sb,
void *bitmap)
{
uint32_t checksum = 0;
if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
uint32_t blocks_per_group = ext4_get32(sb, blocks_per_group);
/* First calculate crc32 checksum against fs uuid */
checksum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid,
sizeof(sb->uuid));
/* Then calculate crc32 checksum against block_group_desc */
checksum = ext4_crc32c(checksum, bitmap, blocks_per_group / 8);
}
return checksum;
}
