ref: 733c5d6645b133b60d304c38fcb1398f94d0618c
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; }