at ext4_trim_all_free() comment, there is no longer an @e4b parameter,
instead it is @group.
Reported-by: NAndreas Dilger <adilger@dilger.ca>
Signed-off-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>