In poweroff conditions BlueFS can create corrupted files
It is possible to create condition in which a BlueFS contains file that is corrupted.
It can happen when BlueFS replay log is on device A and we just wrote to device B.
1) write to file h1 on SLOW device
2) flush h1 (and trigger h1 mark to be added to bluefs replay log, but no fdatasync yet)
3) write to file h2 on DB
4) fsync h2 (forces replay log to be written, after fdatasync to DB)
In result we have file h1 that is properly declared in replay log, but with uninitialized content.