[PATCH] shrink_list(): check PageSwapCache() after add_to_swap()

[PATCH] shrink_list(): check PageSwapCache() after add_to_swap()

From: Nikita Danilov <Nikita@Namesys.COM>

shrink_list() checks PageSwapCache() before calling add_to_swap(), this
means that anonymous page that is going to be added to the swap right
now these checks return false and:

 (*) it will be unaccounted for in nr_mapped, and

 (*) it won't be written to the swap if gfp_flags include __GFP_IO but
     not __GFP_FS.

(Both will happen only on the next round of scanning.)

Patch below just moves may_enter_fs initialization down. I am not sure
about (*nr_mapped) increase though.