mballoc: add comments to ext4_mb_mark_free_simple()
mballoc: add comments to ext4_mb_mark_free_simple()

This patch adds comments to ext4_mb_mark_free_simple to make it more
understandable.

Signed-off-by: Coly Li <ccd45009bd95c180e6a40ba19be3cebf81575bfd@taobao.com>
Cc: Alex Tomas <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@clusterfs.com>
Cc: Theodore Tso <4ed386e0495d3e109932df055831d9ec2f824927@google.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs