[Pkg-sysvinit-devel] Bug#872039: why the severity?

[Adam Borowski]

> Reason for Severity=serious: This leaves /var (or other
> filesystems) in an unclean state, so could possibly lead to
> data loss!

Please tell me why this would be serious: any filesystem from this millenium
can handle unclean shutdown fine -- especially if there's a sync before
reboot/poweroff.

For example, on my desktop, non-trivial subvolume layout leads to:

[ ok ] Unmounting temporary filesystems...done.
[ ok ] Deactivating swap...done.
[....] Unmounting weak filesystems...umount: /srv/chroots/tmp/home: target is busy.
umount: /srv/chroots: target is busy.
umount: /home: target is busy.
failed.
[ ok ] Unmounting local filesystems...done.
[16396.379093] BTRFS info (device sda1): using free space tree
[ ok ] Stopping the hotplug events dispatcher: systemd-udevd.
[info] Will now halt.
[16399.026813] kvm: exiting hardware virtualization
[16399.031944] sd 2:0:0:0: [sdb] Synchronizing SCSI cache
[16399.037624] sd 2:0:0:0: [sdb] Stopping disk
[16400.789927] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[16400.798161] sd 0:0:0:0: [sda] Stopping disk
[16402.943670] ACPI: Preparing to enter system sleep state S5
[16403.045314] reboot: Power down

Which I did not bother to look into for many years, yet there's never been
any data loss.  A sudden _unexpected_ failure (such as due to power
blackout, PSU being flaky, etc) may lead to losing contents of files written
seconds before the failure, but if the filesystem itself needs a fsck,
please report a serious bug against the filesystem in question (yeah,
they're parts of the kernel rather than individual Debian packages, but
you know where to find their maintainers).  An orderly shutdown that doesn't
fully unmount a filesystem doesn't count as unexpected.

Fixing this bug in general is not really possible, as enumerating some
namespaces may be not trivial, processes might be stuck in D state due to
some bug, etc.  Thus, a sync is supposed to be enough.

Filesystems that can't take unclean shutdown do exist (vfat, ext2), but no
one seriously considers running a system from them -- and a sync with no
further writes means no data loss either.


Meow!
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