Merge remote-tracking branch 'aosp/upstream-f2fs-stable-linux-4.19.y' into android-4.19

* aosp/upstream-f2fs-stable-linux-4.19.y:
  f2fs: fix quota_sync failure due to f2fs_lock_op
  f2fs: support read iostat
  f2fs: Fix the accounting of dcc->undiscard_blks
  f2fs: fix to handle error path of f2fs_ra_meta_pages()
  f2fs: report the discard cmd errors properly
  f2fs: fix long latency due to discard during umount
  f2fs: add tracepoint for f2fs iostat
  f2fs: introduce sysfs/data_io_flag to attach REQ_META/FUA
  ubifs: wire up FS_IOC_GET_ENCRYPTION_NONCE
  f2fs: wire up FS_IOC_GET_ENCRYPTION_NONCE
  ext4: wire up FS_IOC_GET_ENCRYPTION_NONCE
  fscrypt: add FS_IOC_GET_ENCRYPTION_NONCE ioctl

Change-Id: I976edb3288576caa0c56eff202690b1159fcf827
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>