From: "Huang Ying" <ying.huang@xxxxxxxxx>
When VMA based swap readahead is introduced in commit ec560175c0b6
("mm, swap: VMA based swap readahead"), "struct vma_swap_readahead" is
defined to describe the readahead window. Because we wanted to save
the PTE entries in the struct at that time. But after commit
4f8fcf4ced0b ("mm/swap: swap_vma_readahead() do the
pte_offset_map()"), we no longer save PTE entries in the struct. The
size of the struct becomes so small, that it's better to use the
fields of the struct directly. This can simplify the code to improve
the code readability. The line number of source code reduces too.
A theoretical underflow issue and some related code cleanup is done in
the series too.
Best Regards,
Huang, Ying
