[PATCH v2 2/2] virdevmapper: Handle kernel without device-mapper support

[Peter Krempa]

On Tue, Aug 18, 2020 at 11:30:25 +0200, Michal Privoznik wrote:
> In one of my latest patch (v6.6.0~30) I was trying to remove
> libdevmapper use in favor of our own implementation. However, the
> code did not take into account that device mapper can be not
> compiled into the kernel (e.g. be a separate module that's not
> loaded) in which case /proc/devices won't have the device-mapper
> major number and thus virDevMapperGetTargets() and/or
> virIsDevMapperDevice() fails.

I'd probably mention the fact that all callers just configure some
aspects of the DM devices thus it's guaranteed that there's nothing to
do in this case and it's safe to ignore the error. Just I can't seem to
come up with a nice formulation.

> Fixes: 22494556542c676d1b9e7f1c1f2ea13ac17e1e3e
> Reported-by: Andrea Bolognani <abologna at redhat.com>
> Reported-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---

Regardless of the above:

Reviewed-by: Peter Krempa <pkrempa at redhat.com>

>  src/util/virdevmapper.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)