NFSD: Simplify struct knfsd_fh

Compilers are allowed to insert padding and reorder the
fields in a struct, so using a union of an array and a
struct in struct knfsd_fh is not reliable.

The position of elements in an array is more reliable.

Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

fs/nfsd/nfsfh.h

@@ -49,17 +49,14 @@ struct knfsd_fh {
 					 * Points to the current size while
 					 * building a new file handle.
 					 */
-	union {
-		char			fh_raw[NFS4_FHSIZE];
-		struct {
-			u8		fh_version;	/* == 1 */
-			u8		fh_auth_type;	/* deprecated */
-			u8		fh_fsid_type;
-			u8		fh_fileid_type;
-		};
-	};
+	u8		fh_raw[NFS4_FHSIZE];
 };
 
+#define fh_version		fh_raw[0]
+#define fh_auth_type		fh_raw[1]
+#define fh_fsid_type		fh_raw[2]
+#define fh_fileid_type		fh_raw[3]
+
 static inline u32 *fh_fsid(const struct knfsd_fh *fh)
 {
 	return (u32 *)&fh->fh_raw[4];