The folio equivalent of memcpy_page(). It should correctly and
efficiently manage large folios:
- If one, neither or both is highmem
- If (either or both) offset+len crosses a page boundary
- If the two offsets are congruent or not
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>