Re: [PATCH 1/1] dm raid: fix compat_features validation

From: Mike Snitzer
Date: Tue Oct 11 2016 - 10:47:38 EST

On Tue, Oct 11 2016 at 10:28am -0400,
Andy Whitcroft <apw@xxxxxxxxxxxxx> wrote:

> In commit ecbfb9f118bce4 ("dm raid: add raid level takeover support") a new
> compatible feature flag was added. Validation for these compat_features
> was added but this only passes for new raid mappings with this feature
> flag. This causes previously created raid mappings to be failed at import.
> Check compat_features for any valid combinations.
> Fixes: ecbfb9f118bce4 ("dm raid: add raid level takeover support")
> BugLink:
> Signed-off-by: Andy Whitcroft <apw@xxxxxxxxxxxxx>
> ---
> drivers/md/dm-raid.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> It very much looks like these are intended to be optional extended feature
> flags. That we should be accepting any valid flag and rejecting any bit
> not in that set. We should however not be ensuring that specific bits
> are actually set. Certainly as things stand raid sets built on previous
> kernel versions cannot be assembled.

Right, your patch looks good to me. But I'll wait for confirmation from
Heinz before I stage your fix.