On Fri, Feb 21, 2020 at 09:04:34AM -0800, Christoph Hellwig wrote:

Given that blk_ksm_get_slot_for_key returns a signed keyslot that
can return errors, and the only callers stores it in a signed variable
I think this function should take a signed slot as well, and the check
for a non-negative slot should be moved here from the only caller.

Actually looking over the code again I think it might be better to
return only the error code (and that might actually be a blk_status_t),
and then use an argument to return a pointer to the actual struct
keyslot.  That gives us much easier to understand code and better
type safety.