[dm-devel] [PATCH] 11-dm-mpath.rules: Fix udev rule processing during coldplug

[Benjamin Marzinski]

On Tue, Jun 02, 2020 at 05:54:43PM +0200, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
> 
> DM_SUBSYSTEM_UDEV_FLAG0 is used to indicate that upper layer
> udev rules don't need to be processed for multipath maps, e.g.
> for map reloads.
> 
> However, this can fail if maps were created during initrd processing,
> but udev processing for the change events of these maps didn't
> complete because udevd was killed to switch root. So, in the coldplug
> case, play safe and process the rules once more.
> 
> Signed-off-by: Martin Wilck <mwilck at suse.com>
Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>

> ---
>  multipath/11-dm-mpath.rules | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/multipath/11-dm-mpath.rules b/multipath/11-dm-mpath.rules
> index cd522e8c..34c21fd1 100644
> --- a/multipath/11-dm-mpath.rules
> +++ b/multipath/11-dm-mpath.rules
> @@ -52,8 +52,13 @@ LABEL="mpath_action"
>  # something that should be reacted upon since it would be useless extra work.
>  # It's exactly mpath's job to provide *seamless* device access to any of the
>  # paths that are available underneath.
> +# Exception: On cold-plug, if the map had already been set up before,
> +# do process upper layers, because rule processing may not necessarily have
> +# completed during initrd processing.
> +ACTION=="add", ENV{.MPATH_DEVICE_READY_OLD}=="1", GOTO="process_reload"
>  ENV{DM_SUBSYSTEM_UDEV_FLAG0}=="1", \
>  	ENV{DM_ACTIVATION}="0", ENV{MPATH_UNCHANGED}="1"
> +LABEL="process_reload"
>  
>  # For path failed or reinstated events, unset DM_ACTIVATION.
>  # This is similar to the DM_SUBSYSTEM_UDEV_FLAG0 case above.
> -- 
> 2.26.2