On Fri, Jan 12, 2018 at 12:07:57PM +0100, Florian Weimer wrote:
If the system crashes before the file data has been written to disk, the
file system recovery upon the next mount may restore a partially
rewritten temporary file under the non-temporary (final) name (after the
rename operation).
Some file systems perform an implicit fsync before renaming a file over
another one, but XFS does not, for example.
At least on Linux no file system performs an actual fsync equivalent.
A few do start a writeout, but don't actually wait on it.