Currently we sometimes used block_write_full_page() and sometimes
ext4_bio_write_page() for writeback (depending on mount options and call
path). Let's always use ext4_bio_write_page() to simplify things a bit.
Reviewed-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>