Re: s6-linux-init: Actions after unmounting filesystems

[Brett Neumeier <bneumeier@gmail.com>]

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On Sat, Aug 17, 2019 at 2:20 PM Guillermo <gdiazhartusch@gmail.com> wrote:

> There are certain setups that require doing something after
> filesystems are unmounted. Two examples are LVM logical volumes and
> LUKS encrypted volumes, but I suppose there must be more cases. In any
> such setup, the shutdown sequence would include a 'vgchange -a n'
> command or 'cryptsetup close' command after filesystems are unmounted.
>

How important are these cases?

I have not inspected the code to see what cryptsetup close does, aside from
remove the encrypted device mapping for the encrypted volume; nor have I
looked at the LVM code to see if it does anything other than remove device
mapping. But in either case, what I generally do on my systems is simply
unmount volumes (or in the case of the root filesystem, remount it
read-only), sync to make sure all dirty buffers are written, and then just
shut down/reboot/whatever.

Leaving LVM and encrypted volumes active has never caused any problems for
me.

It seems worthwhile to ask whether those examples are real problems that
need to be addressed, since all of the proposed solutions have some level
of hairiness about them. And if those examples are *not* real issues, it
might be worthwhile to ask if there are other examples that *are*.

-- 
Brett Neumeier (bneumeier@gmail.com)