EXT4_EPOCH_BITS 401 fs/ext4/ext4.h #define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1) EXT4_EPOCH_BITS 402 fs/ext4/ext4.h #define EXT4_NSEC_MASK (~0UL << EXT4_EPOCH_BITS) EXT4_EPOCH_BITS 2152 fs/ext4/super.c sb->s_time_gran = 1 << (EXT4_EPOCH_BITS - 2);