[PATCH 0/2] avoid prepare_creds in faccessat when possible

[Mateusz Guzik <mguzik@redhat.com>]

Sometimes faccessat needs to modify current thread's credentials, but
calls prepare_creds unconditionally.

However, typically resulting credentials are identical to original ones
and in that case newcredentials are unnecessary. We can detect this before
allocating anything.

This patch series adds a helper which allows comparing capability sets and
modifies faccessat to use it.

Mateusz Guzik (2):
  CAPABILITIES: add cap_isequal helper
  fs: avoid unnecessary prepare_creds in faccessat

 fs/open.c                  | 53 ++++++++++++++++++++++++++++++----------------
 include/linux/capability.h | 10 +++++++++
 2 files changed, 45 insertions(+), 18 deletions(-)

-- 
1.8.3.1