f2fs: speed up defragment on sparse file

We have supported to get next page offset with valid mapping crossing
hole in f2fs_map_blocks, utilizing it to speed up defragment on sparse
file.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2 files changed