NFSD: Add nfsd4_encode_fattr4_acl_trueform_scope

The FATTR4_ACL_TRUEFORM_SCOPE attribute indicates the granularity at
which the ACL model can vary: per file object, per file system, or
uniformly across the entire server.

In Linux, the ACL model is determined by the SB_POSIXACL superblock
flag, which applies uniformly to all files within a file system.
Different exported file systems can have different ACL models, but
individual files cannot differ from their containing file system.
ACL_SCOPE_FILE_SYSTEM accurately reflects this behavior.

Signed-off-by: Rick Macklem <rmacklem@uoguelph.ca>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: rmacklem

fs/nfsd/nfs4xdr.c

@@ -3484,6 +3484,14 @@ static __be32 nfsd4_encode_fattr4_acl_trueform(struct xdr_stream *xdr,
 	return nfs_ok;
 }
 
+static __be32 nfsd4_encode_fattr4_acl_trueform_scope(struct xdr_stream *xdr,
+						     const struct nfsd4_fattr_args *args)
+{
+	if (!xdrgen_encode_aclscope4(xdr, ACL_SCOPE_FILE_SYSTEM))
+		return nfserr_resource;
+	return nfs_ok;
+}
+
 #endif /* CONFIG_NFSD_V4_POSIX_ACLS */
 
 static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
@@ -3596,8 +3604,10 @@ static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
 
 #ifdef CONFIG_NFSD_V4_POSIX_ACLS
 	[FATTR4_ACL_TRUEFORM]		= nfsd4_encode_fattr4_acl_trueform,
+	[FATTR4_ACL_TRUEFORM_SCOPE]	= nfsd4_encode_fattr4_acl_trueform_scope,
 #else
 	[FATTR4_ACL_TRUEFORM]		= nfsd4_encode_fattr4__noop,
+	[FATTR4_ACL_TRUEFORM_SCOPE]	= nfsd4_encode_fattr4__noop,
 #endif
 };