ref: b959508d906a6f7c98fe03b8bfd520370061f20f
dir: /sys/src/cmd/ext4srv/ext4_super.c/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_misc.h"
#include "ext4_debug.h"
#include "ext4_super.h"
#include "ext4_crc32.h"
u32int ext4_block_group_cnt(struct ext4_sblock *s)
{
u64int blocks_count = ext4_sb_get_blocks_cnt(s);
u32int blocks_per_group = ext4_get32(s, blocks_per_group);
u32int block_groups_count = (u32int)(blocks_count / blocks_per_group);
if (blocks_count % blocks_per_group)
block_groups_count++;
return block_groups_count;
}
u32int ext4_blocks_in_group_cnt(struct ext4_sblock *s, u32int bgid)
{
u32int block_group_count = ext4_block_group_cnt(s);
u32int blocks_per_group = ext4_get32(s, blocks_per_group);
u64int total_blocks = ext4_sb_get_blocks_cnt(s);
if (bgid < block_group_count - 1)
return blocks_per_group;
return (u32int)(total_blocks - ((block_group_count - 1) * blocks_per_group));
}
u32int ext4_inodes_in_group_cnt(struct ext4_sblock *s, u32int bgid)
{
u32int block_group_count = ext4_block_group_cnt(s);
u32int inodes_per_group = ext4_get32(s, inodes_per_group);
u32int 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));
}
static u32int ext4_sb_csum(struct ext4_sblock *s)
{
return ext4_crc32c(EXT4_CRC32_INIT, s,
offsetof(struct ext4_sblock, checksum));
}
static bool ext4_sb_verify_csum(struct ext4_sblock *s)
{
if (!ext4_sb_feature_ro_com(s, EXT4_FRO_COM_METADATA_CSUM))
return true;
if (s->checksum_type != to_le32(EXT4_CHECKSUM_CRC32C))
return false;
return s->checksum == to_le32(ext4_sb_csum(s));
}
void ext4_sb_set_csum(struct ext4_sblock *s)
{
if (!ext4_sb_feature_ro_com(s, EXT4_FRO_COM_METADATA_CSUM))
return;
s->checksum = to_le32(ext4_sb_csum(s));
}
int ext4_sb_write(struct ext4_blockdev *bdev, struct ext4_sblock *s)
{
ext4_sb_set_csum(s);
return ext4_block_writebytes(bdev, EXT4_SUPERBLOCK_OFFSET, s,
EXT4_SUPERBLOCK_SIZE);
}
int ext4_sb_read(struct ext4_blockdev *bdev, struct ext4_sblock *s)
{
return ext4_block_readbytes(bdev, EXT4_SUPERBLOCK_OFFSET, s,
EXT4_SUPERBLOCK_SIZE);
}
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;
}
static inline int is_power_of(u32int a, u32int b)
{
while (1) {
if (a < b)
return 0;
if (a == b)
return 1;
if ((a % b) != 0)
return 0;
a = a / b;
}
}
bool ext4_sb_sparse(u32int group)
{
if (group <= 1)
return 1;
if (!(group & 1))
return 0;
return (is_power_of(group, 7) || is_power_of(group, 5) ||
is_power_of(group, 3));
}
bool ext4_sb_is_super_in_bg(struct ext4_sblock *s, u32int group)
{
if (ext4_sb_feature_ro_com(s, EXT4_FRO_COM_SPARSE_SUPER) &&
!ext4_sb_sparse(group))
return false;
return true;
}
static u32int ext4_bg_num_gdb_meta(struct ext4_sblock *s, u32int group)
{
u32int dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
u32int metagroup = group / dsc_per_block;
u32int first = metagroup * dsc_per_block;
u32int last = first + dsc_per_block - 1;
if (group == first || group == first + 1 || group == last)
return 1;
return 0;
}
static u32int ext4_bg_num_gdb_nometa(struct ext4_sblock *s, u32int group)
{
if (!ext4_sb_is_super_in_bg(s, group))
return 0;
u32int dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
u32int db_count =
(ext4_block_group_cnt(s) + dsc_per_block - 1) / dsc_per_block;
if (ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG))
return ext4_sb_first_meta_bg(s);
return db_count;
}
u32int ext4_bg_num_gdb(struct ext4_sblock *s, u32int group)
{
u32int dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
u32int first_meta_bg = ext4_sb_first_meta_bg(s);
u32int metagroup = group / dsc_per_block;
if (!ext4_sb_feature_incom(s,EXT4_FINCOM_META_BG) ||
metagroup < first_meta_bg)
return ext4_bg_num_gdb_nometa(s, group);
return ext4_bg_num_gdb_meta(s, group);
}
u32int ext4_num_base_meta_clusters(struct ext4_sblock *s,
u32int block_group)
{
u32int num;
u32int 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);
}
u32int clustersize = 1024 << ext4_get32(s, log_cluster_size);
u32int cluster_ratio = clustersize / ext4_sb_get_block_size(s);
u32int v =
(num + cluster_ratio - 1) >> ext4_get32(s, log_cluster_size);
return v;
}