[PATCH v2] smackfs: restrict bytes count in smackfs write functions

[Sabyrzhan Tasbolatov]

> if PAGE_SIZE >= SMK_LOADSIZE all legitimate requests can be made
> using PAGE_SIZE as a limit. Your example with 19990 spaces before
> the data demonstrates that the interface is inadequately documented.
> Tizen and Automotive Grade Linux are going to be fine with a PAGE_SIZE
> limit. The best way to address this concern is to go ahead with the
> PAGE_SIZE limit and create ABI documents for the smackfs interfaces.
> I will take your patch for the former and create a patch for the latter.

Please let me know if there is anything else required for this patch.
AFAIU, we agreed with PAGE_SIZE as the limit.