f2fs-for-5.6 In this series, we've implemented transparent compression experimentally. It supports LZO and LZ4, but will add more later as we investigate in the field more. At this point, the feature doesn't expose compressed space to user directly in order to guarantee potential data updates later to the space. Instead, the main goal is to reduce data writes to flash disk as much as possible, resulting in extending disk life time as well as relaxing IO congestion. Alternatively, we're also considering to add ioctl() to reclaim compressed space and show it to user after putting the immutable bit. Enhancement: - add compression support - avoid unnecessary locks in quota ops - harden power-cut scenario for zoned block devices - use private bio_set to avoid IO congestion - replace GC mutex with rwsem to serialize callers Bug fix: - fix dentry consistency and memory corruption in rename()'s error case - fix wrong swap extent reports - fix casefolding bugs - change lock coverage to avoid deadlock - avoid GFP_KERNEL under f2fs_lock_op And, we've cleaned up sysfs entries to prepare no debugfs.