[pkg-dhcp-devel] Bug#758882: Bug#758882: isc-dhcp-client: dhclient prevents remounting / in read-only when jessie booted in recovery mode

[Michael Gilbert]

control: severity -1 wishlist
control: reassign -1 rescue-mode
control: retitle -1 rescue-mode: option to select mounting as ro or rw

On Fri, Aug 22, 2014 at 7:59 AM, Olivier Berger wrote:
> I'm not sure this really belongs to isc-dhcp-client, and may deserve attention from other maintainers, but I couldn't find a better place for reportbug.

As mentioned elsewhere ro can be passed as a kernel option.  Or you can do

# mount -o remount,ro /target

before entering the target.

> If a debian jessie system is rebooted with grub's default "recovery mode", and if there's no separate /var partition, the / partition cannot be remunted read-only, because there's a lease file used by dhclient inside /var.
>
> mount -n -o remount,ro will report : mount: / is busy
>
> Indeed /var/lib/dhcp/dhclient.eth0.leases is reported as opened in w mode by lsof.
>
> I believed it may not be ideal to keep dhclient running when in recovery mode, although I'm not qualified enough to know whether it's systemd's duty to stop it for instance.

I did some testing.  The network is brought up and configured in the
d-i environment, not the rescue mode target's environment, so for my
testing dhclient never got launched.  Can you better describe the
exact steps to recreate the problem?

I think what you're really looking for is an option in the rescue mode
dialogs to select whether mounting is attempted as ro or rw.

Best wishes,
Mike