BlueFS truncate() and poweroff 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 and truncated file.
1) write to file h1 on SLOW device
2) flush h1 (initiate data transfer, but no fdatasync yet)
3) truncate h1
4) write to file h2 on DB
5) 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.
This happens even with
I think it is regression introduced by above fix.