Comment 8 for bug 570805

I second that, i love to see some background info!

But it looks like either the release notes or the ext4 documenation needs updating:

===
Release notes
===
`ext4` does not guarantee atomic renames of
new files over existing files in the event of a
power failure shortly after the rename

===
ext4 docs ( http://www.mjmwired.net/kernel/Documentation/filesystems/ext4.txt#338 )
===
the data blocks of the new file are forced
to disk before the rename() operation is
committed. This provides roughly the same level
of guarantees as ext3, and avoids the
"zero-length" problem that can happen when a
system crashes before the delayed allocation
blocks are forced to disk.