/*
* init. the fs meta data, return the block size bits.
*/
static int ext2_fs_init(struct fs_info *fs)
{
struct disk *disk = fs->fs_dev->disk;
struct ext2_sb_info *sbi;
struct ext2_super_block sb;
struct cache *cs;
/* read the super block */
disk->rdwr_sectors(disk, &sb, 2, 2, 0);
/* check if it is ext2, since we also support btrfs now */
if (sb.s_magic != EXT2_SUPER_MAGIC)
return -1;
sbi = malloc(sizeof(*sbi));
if (!sbi) {
malloc_error("ext2_sb_info structure");
return -1;
}
fs->fs_info = sbi;
if (sb.s_magic != EXT2_SUPER_MAGIC) {
printf("ext2 mount error: it's not a EXT2/3/4 file system!\n");
return 0;
}
fs->sector_shift = disk->sector_shift;
fs->block_shift = sb.s_log_block_size + 10;
fs->sector_size = 1 << fs->sector_shift;
fs->block_size = 1 << fs->block_shift;
sbi->s_inodes_per_group = sb.s_inodes_per_group;
sbi->s_blocks_per_group = sb.s_blocks_per_group;
sbi->s_inodes_per_block = BLOCK_SIZE(fs) / sb.s_inode_size;
if (sb.s_desc_size < sizeof(struct ext2_group_desc))
sb.s_desc_size = sizeof(struct ext2_group_desc);
sbi->s_desc_per_block = BLOCK_SIZE(fs) / sb.s_desc_size;
sbi->s_groups_count = (sb.s_blocks_count - sb.s_first_data_block
+ EXT2_BLOCKS_PER_GROUP(fs) - 1)
/ EXT2_BLOCKS_PER_GROUP(fs);
sbi->s_first_data_block = sb.s_first_data_block;
sbi->s_inode_size = sb.s_inode_size;
/* Volume UUID */
memcpy(sbi->s_uuid, sb.s_uuid, sizeof(sbi->s_uuid));
/* Initialize the cache, and force block zero to all zero */
cache_init(fs->fs_dev, fs->block_shift);
cs = _get_cache_block(fs->fs_dev, 0);
memset(cs->data, 0, fs->block_size);
cache_lock_block(cs);
return fs->block_shift;
}
/*
* Check for a particular BLOCK in the block cache,
* and if it is already there, just do nothing and return;
* otherwise load it from disk and update the LRU link.
* Return the data pointer.
*/
const void *get_cache(struct device *dev, block_t block)
{
struct cache *cs;
cs = _get_cache_block(dev, block);
if (cs->block != block) {
cs->block = block;
getoneblk(dev->disk, cs->data, block, dev->cache_block_size);
}
return cs->data;
}
