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

From: Heinz Mauelshagen
Date: Tue Oct 11 2016 - 11:45:06 EST

On 10/11/2016 05:38 PM, Andy Whitcroft wrote:
On Tue, Oct 11, 2016 at 05:04:34PM +0200, Heinz Mauelshagen wrote:

good catch.

We should rather check for V190 support only in case any
compat feature flags are actually set.

+ if (le32_to_cpu(sb->compat_features) &&
+ le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190)
rs->ti->error = "Unable to assemble array: Unknown flag(s)
in compatible feature flags";
return -EINVAL;
If the feature flags are single bit combinations then I believe the
below does check exactly that. Checking for no 1s outside of the
expected features, caring not for the value of the valid bits:

+ if (le32_to_cpu(sb->compat_features) & ~(FEATURE_FLAG_SUPPORTS_V190)) {

with the possibilty to or in additional feature bits as they are added.

I prefer this to be easier readable.


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