[f2fs-dev][PATCH v2 04/10] f2fs: introduce universal lookup/update interface of extent cache

In this patch, we do these jobs: 1. rename {check,update}_extent_cache to {lookup,update}_extent_info; 2. introduce universal lookup/update interface of extent cache: f2fs_{lookup,update}_extent_cache including above two real functions, then export them to function callers. So after above

[f2fs-dev][PATCH v2 04/10] f2fs: introduce universal lookup/update interface of extent cache

In this patch, we do these jobs: 1. rename {check,update}_extent_cache to {lookup,update}_extent_info; 2. introduce universal lookup/update interface of extent cache: f2fs_{lookup,update}_extent_cache including above two real functions, then export them to function callers. So after above