current_cred() can only be changed by 'current', and
cred->group_info is never changed. If a new group_info is
needed, a new 'cred' is created.
Consequently it is always safe to access
current_cred()->group_info
without taking any further references.
So drop the refcounting and the incorrect rcu_dereference().
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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