f2fs-for-5.15-rc1 In this cycle, we've addressed some performance issues such as lock contention, misbehaving compress_cache, allowing extent_cache for compressed files, and new sysfs to adjust ra_size for fadvise. In order to diagnose the performance issues quickly, we also added an iostat which shows the IO latencies periodically. On the stability side, we've found two memory leakage cases in the error path in compression flow. And, we've also fixed various corner cases in fiemap, quota, checkpoint=disable, zstd, and so on. Enhancement: - avoid long checkpoint latency by releasing nat_tree_lock - collect and show iostats periodically - support extent_cache for compressed files - add a sysfs entry to manage ra_size given fadvise(POSIX_FADV_SEQUENTIAL) - report f2fs GC status via sysfs - add discard_unit=%s in mount option to handle zoned device Bug fix: - fix two memory leakages when an error happens in the compressed IO flow - fix commpress_cache to get the right LBA - fix fiemap to deal with compressed case correctly - fix wrong EIO returns due to SBI_NEED_FSCK - fix missing writes when enabling checkpoint back - fix quota deadlock - fix zstd level mount option In addition to the above major updates, we've cleaned up several code paths such as dio, unnecessary operations, debugfs/f2fs/status, sanity check, and typos.