NFS/NFSD/SUNRPC: replace generic creds with 'struct cred'.

SUNRPC has two sorts of credentials, both of which appear as
"struct rpc_cred".
There are "generic credentials" which are supplied by clients
such as NFS and passed in 'struct rpc_message' to indicate
which user should be used to authorize the request, and there
are low-level credentials such as AUTH_NULL, AUTH_UNIX, AUTH_GSS
which describe the credential to be sent over the wires.

This patch replaces all the generic credentials by 'struct cred'
pointers - the credential structure used throughout Linux.

For machine credentials, there is a special 'struct cred *' pointer
which is statically allocated and recognized where needed as
having a special meaning.  A look-up of a low-level cred will
map this to a machine credential.

Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index 1ba717b..5552fa8 100644
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -500,25 +500,18 @@ nfs_proc_readdir(struct dentry *dentry, const struct cred *cred,
 		.count		= count,
 		.pages		= pages,
 	};
-	struct auth_cred acred = {
-		.cred		= cred,
-	};
 	struct rpc_message	msg = {
 		.rpc_proc	= &nfs_procedures[NFSPROC_READDIR],
 		.rpc_argp	= &arg,
-		.rpc_cred	= rpc_lookup_generic_cred(&acred,
-							  0, GFP_NOFS),
+		.rpc_cred	= cred,
 	};
 	int			status;
 
 	dprintk("NFS call  readdir %d\n", (unsigned int)cookie);
-	if (!msg.rpc_cred)
-		return -ENOMEM;
 	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
 
 	nfs_invalidate_atime(dir);
 
-	put_rpccred(msg.rpc_cred);
 	dprintk("NFS reply readdir: %d\n", status);
 	return status;
 }