Reg-filling of super_block in a filesystem

[SATHISH.J]

Hi,
In the minix_read_super() function we try to read a block number 1 from
the device. 

lock_super(s);
        set_blocksize(dev, BLOCK_SIZE);/*defined in fs/buffer.c*/
        if (!(bh = bread(dev,1,BLOCK_SIZE)))
                goto out_bad_sb;
        ms = (struct minix_super_block *) bh->b_data;
        

In the above, bh->b_data is assigned to ms. This minix_read_super function
gets called when we mount the minix file system. Then when does this block
1 of the device gets filled. Does it get filled when we do mkfs? Please
let me know this.

Thanks in advance.
Warm regards,
sathish.j