Ext4 doesn't guarantee that write file.new / close file.new rename file.new to file will mean data in file.new makes it to file atomically. The rename may happen with previous contents of file.new and then later update to new contents See docs for noauto_da_alloc So rebooting the device during JournaledFile.commit may mean we are left with an empty file. Bug: 18590558 Change-Id: I35322c82871bed30c2c6ebbd1388338f0471f3ba