[PATCH 13/35] monitor: disable nvmf-autoconnect udev rules in autoconnect mode

[Sagi Grimberg]

>> On 1/26/21 12:33 PM, mwilck at suse.com wrote:
>>> From: Martin Wilck <mwilck at suse.com>
>>>
>>> If autoconnect is enabled, disable the respective udev rules
>>> by symlinking /run/udev/rules.d to /dev/null, in order to avoid
>>> the connections being set up by the monitor and the udev workers
>>> at the same time. This is probably the preferred mode of operation
>>> for the monitor.
>>>
>>> Users can override this by copying 70-nvmf-autoconnect.rules
>>> from /usr/lib/udev/rules.d to /etc/udev/rules.d (/etc/udev/rules.d
>>> takes precedence over /run/udev/rules.d).
>>>
>>> If the symlink can't be created for some reason, autoconnect will
>>> be disabled. There is  only one exception: If
>>> /run/udev/rules.d/70-nvmf-autoconnect.rules already points to
>>> /dev/null at startup, autoconnect can be left on, but the symlink
>>> isn't removed on exit.
>>
>> Can't we just document that just one should be enabled and skip
>> the entire thing? Especially when its not critical if both run..
> 
> It's not critical, but it makes no sense to have the rules enabled when
> the monitor runs. And having to mask/unmask them manually is a pain.
> 
> It could be done in the systemd service file using ExecStartPre /
> ExecStopPost, with small restrictions (we couldn't distinguish whether
> the rules were already masked before we started). That would be more
> transparent for users.

Maybe 'Conflicts' can help here?