BACKPORT: f2fs: fix to mitigate overhead of f2fs_zero_post_eof_page()

f2fs_zero_post_eof_page() may cuase more overhead due to invalidate_lock
and page lookup, change as below to mitigate its overhead:
- check new_size before grabbing invalidate_lock
- lookup and invalidate pages only in range of [old_size, new_size]

Bug: 432527227
[Chao: adjust the code]
(cherry picked from commit c2f7c32b)
Change-Id: If1f91fb4a7651272e90ebc63dd9d691d5bd323fb
Fixes: ba8dac35 ("f2fs: fix to zero post-eof page")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>