mksfs.c add_entry问题

[hhxx1994]

static void
add_entry(struct sfs_fs *sfs, struct cache_inode *current, struct cache_inode *file, const char *name) {
    //sfs_disk_entry
    static struct sfs_entry __entry, *entry = &__entry;
    //current必须是目录类型的inode
    assert(current->inode.type == SFS_TYPE_DIR && strlen(name) <= SFS_MAX_FNAME_LEN);
    //设置block number id和文件名称
    entry->ino = file->ino, strcpy(entry->name, name);
    // 下一个 block ino
    uint32_t entry_ino = sfs_alloc_ino(sfs);
    // 都是从 entry_no * blocksize开始写，这个意思是 一个entry占有一个disk block 了
    //               data ,  len=256          , block number id 
    write_block(sfs, entry, sizeof(entry->name), entry_ino);
    
    // printf("entry->name: %s entry_ino: %d  len:%d \n", entry->name, entry_ino ,sizeof(entry->name));
    
    // 在sfs->blocks中添加一个cache_block和相应的ino
    // 就是将entry_ino 记录到current->inode->direct 或则 current->inode->indirect 或者 current->inode->db_indirect
    //current->inode->direct[current->nblks] = entry_ino
    // 给目录 current 添加一个表示 文件或者目录的sfs_entry数据
    append_block_slot(sfs, current, entry_ino, name);
    //append_block(sfs, current, sizeof(entry->name), entry_ino, name);
    file->inode.nlinks ++;
}

write_block(sfs, entry, sizeof(entry->name), entry_ino);
这里为什么是sizeof(entry->name),而不是sizeof(sfs_entry)