On Mon, Dec 10, 2018 at 07:37:57PM +0800, Qu Wenruo wrote: > >>> Also please use explicit bool type: > >>> > >>> bool xxxx:1 > >> > >> Is this valid? Haven't seen such usage in kernel code IIRC. > > > > git grep 'bool .*:1' | wc -l > > 417 > > grep -IR 'bool .*:1' fs/btrfs/ | wc -l > 0 > > So I guess another cleanup?
No bool bitfields unless there's a space saved in the structure, please. If there are less than 4 bool types in a structure, it's same as 4 bits in u32 and is ok. The bit manipulation needs more instructions, checking zero/non-zero of a byte is typically cheaper. Looking at the structure, the 'int action' can be reduced and the hole to the next u64 has enough bytes to squeeze a number of bools if needed.
