Initial SP4_MACH_CRED implementation

This is version 2 of this patchset including some cleanup, refactoring and fixes a few build issues with different configs.

I also added a few patches:
- WRITE and/or COMMIT support - tested on a hacked nfsd
- map NFS4ERR_WRONG_CRED (an common SP4 error) to EPERM

I meant to include a patch that only uses the machine cred (for 'allow' ops) when the user cred has expired, but after talking with Andy, I decided to wait for his cred expiration patchset to be merged as we'd be touching the same places and possibly duplicating effort.

Weston Andros Adamson (7):
nfs4.1: Minimal SP4_MACH_CRED implementation nfs4.1: Add state protection handler nfs4.1: Add SP4_MACH_CRED cleanup support nfs4.1: Add SP4_MACH_CRED secinfo support nfs4.1: Add SP4_MACH_CRED stateid support nfs4.1: Add SP4_MACH_CRED write and commit support
nfs4: Map NFS4ERR_WRONG_CRED to EPERM

 fs/nfs/nfs4_fs.h          |  67 ++++++++++++++++
 fs/nfs/nfs4proc.c         | 191 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/nfs/nfs4xdr.c          |  72 ++++++++++++++---
 fs/nfs/write.c            |   6 ++
 include/linux/nfs_fs_sb.h |   9 +++
 include/linux/nfs_xdr.h   |  19 +++++
 6 files changed, 346 insertions(+), 18 deletions(-)

1.7.12.4 (Apple Git-37)