EXT2_ADDR_PER_BLOCK_BITS
if (logical_block < (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2)))
[logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)]))
logical_block -= (1 << (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK) * 2));
[logical_block >> (EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK)
[(logical_block >> EXT2_ADDR_PER_BLOCK_BITS (SUPERBLOCK))