On my testing computer lived till today quite outdated Debian Unstable.
As I needed to perform some testing with that which required recent
version of some tools, I bravely did upgrade using aptitude.
After two hours of downloading, packages started to install, but it
crashed while installing linux-kernel-headers. Well as I didn't know in
what shape my last tests kept Debian and XFS filesystem it uses for
root, I rebooted using live CD and ran xfs_repair.
It found several errors, I rebooted and reran aptitude. To my suprise
the problem did not went away, and after another boot using live CD, I
saw that xfs_repair still sees those problems.
Fortunately I noticed that live CD contains quite old xfs_repair and I
used the one which is currently in unstable. And it seems to finally fix
my problem! Now I can finally start my upgrade and it works :-).