Also filed as GNU Savannah bug #29292.
#hurd, 2010, end of May / beginning of June
[runnign sync, but sill unclean filesystem at next boot] <slpz> guillem: when libpager syncs an object, it sends an m_o_lock_request and waits (if the synchronous argument was specified) for a m_o_lock_completed. But m_o_lock_completed only means that dirty pages have been sent to the translator, and this one still needs to write them to the backing storage <slpz> guillem: there's no problem if sync() returns before actually writting the changes to disk, but this also happens when shutting down the translator <slpz> guillem: in theory, locking mechanisms in libpager should prevent this from happening by keeping track of write operations, but this seems to fail in some situations
It helps a lot to run
syncfs --synchronous / before issuing
reboot command. This will prevent most of the uncleanliness.
Of course, ext2fs is meant to be doing this to-disk
synchronization internally upon translator shutdown, but evidently it doesn't
in all cases.
Apparently diskfs simply does not set filesystems as read-only: http://lists.gnu.org/archive/html/bug-hurd/2011-08/msg00024.html.
A patch was applied, and the sync issue does not seem to happen any more.